Introduction

Headache is a common ailment that is often due to a combination of physical and psychological factors. The vast majority are benign and self-limiting and are managed by patients in the community. Only a very small proportion of patients experiencing headache attend emergency departments (ED) for treatment. The challenges are to distinguish potentially life-threatening causes from the more benign, and to effectively manage the pain of headache.

Pathophysiology

The structures in the head capable of producing headache are limited. They include:

The bulk of the intracranial contents, including the parenchyma of the brain, the subarachnoid and pia mater and most of the dura mater, are incapable of producing painful stimuli.

The pathological processes that may cause headache are:

The pathophysiological causes of headache are summarized in Table 8.1.1.

Table 8.1.1 A pathophysiological classification of headache

Assessment

In the assessment of a patient with headache, history is of prime importance. Specific information should be sought about the timing of the headache (in terms of both overall duration and speed of onset), the site and quality of the pain, relieving factors, the presence of associated features such as nausea and vomiting, photophobia and alteration in mental state, medical and occupational history and drug use.

Intensity of the pain is important from the viewpoint of management but is not a reliable indicator of the nature of underlying pathology. This said, sudden, severe headache and chronic, unremitting or progressive headache are more likely to have a serious cause.

Physical examination should include temperature, pulse rate and blood pressure measurements, assessment of conscious state and neck stiffness and neurological examination, including funduscopy (where indicated). Abnormal physical signs are uncommon, but the presence of neurological findings makes a serious cause probable. In addition, a search should be made for sinus, ear, mouth and neck pathology and muscular or superficial temporal artery tenderness.

Headache patterns

Some headaches have ‘classic’ clinical features: these are listed in Table 8.1.2. It must be remembered that, as with all diseases, there is a spectrum of presenting features and the absence of the classic features does not rule out a particular diagnosis. Every patient must be assessed on their merits and, if symptoms persist without reasonable explanation, further investigation should be undertaken.

Table 8.1.2 Classic clinical complexes and cause of headache

Preceded by an aura
Throbbing unilateral headache, nausea		Migraine
Family history
Sudden onset
Severe occipital headache; ‘like a blow’		Subarachnoid haemorrhage
Worst headache ever
Throbbing/constant frontal headache
Worse with cough, leaning forward		Sinusitis
Recent URTI
Pain on percussion of sinuses
Paroxysmal, fleeting pain
Distribution of a nerve		Neuralgia
Trigger manoeuvres cause pain
Hyperalgesia of nerve distribution
Unilateral with superimposed stabbing
Claudication on chewing		Temporal arteritis
Associated malaise, myalgia
Tender artery with reduced pulsation
Persistent, deep-seated headache
Increasing duration and intensity		Tumour: primary or secondary
Worse in morning
Aching in character
Acute, generalized headache
Fever, nausea and vomiting		Meningitis
Altered level of consciousness
Neck stiffness +/– rash
Unilateral, aching, related to eye
Nausea and vomiting		Glaucoma
Raised intraocular pressure
Aching, facial region
Worse at night		Dental cause
Tooth sensitive to heat, pressure

Investigation

For the vast majority of patients with headache no investigation is required. The investigation of suspected subarachnoid haemorrhage and meningitis is discussed elsewhere in this book. If tumour is suspected, the investigations of choice are magnetic resonance imaging (MRI) or a contrast-enhanced computed tomography (CT) scan. An elevated ESR may be supporting evidence for a diagnosis of temporal arteritis. With respect to sinusitis, facial X-rays are of very limited value.

Tension headache

The pathological basis of tension headaches remains unclear, but increased tension of the neck or cranial muscles is a prominent feature. A family history of headaches is common, and there is an association with an injury in childhood or adolescence. The most common precipitants are stress and alteration in sleep patterns.

Aspirin, non-steroidal anti-inflammatory agents (NSAIDs) and paracetamol have all been shown to be effective in the treatment of tension headaches, with success rates between 50% and 70%. Ibruprofen 400 mg or ketoprofen 25–50 mg appear to be the most effective, followed by aspirin 600–1000 mg and paracetamol 1000 mg.

Migraine

Migraine can be a disabling condition for the sufferer. Most migraine headaches are successfully managed by the patient and their general practitioner, but a small number fail to respond or become ‘fixed’, and sufferers may present for treatment at EDs. As most patients (up to 80% in some studies) have tried oral medications prior to presenting, parenterally administered agents are usually indicated for ED treatment.

Migraine is a clinical diagnosis, and in the ED setting a diagnosis of exclusion. Other causes of severe headache, such as subarachnoid haemorrhage and meningitis, must be ruled out before this diagnosis is made. In particular, the response of the headache to anti-migraine therapy should not be used to assume that the cause was migraine. There have been reports that the headaches associated with subarachnoid haemorrhage and meningitis have, on occasion, responded to these agents.

Trigeminal neuralgia

Trigeminal neuralgia is a debilitating condition in which patients describe ‘lightning’- or a ‘hot poker’-like pain that is severe and follows the distribution of the trigeminal nerve. Individual episodes of pain last only seconds, but may recur repeatedly within a short period and can be triggered by minor stimuli such as light touch, eating or drinking, shaving or passing gusts of wind. It is most common in middle or older age.

Introduction

Cerebrovascular disease is the third highest cause of death in developed countries, after heart disease and cancer. A stroke is an acute neurological injury secondary to cerebrovascular disease, either by infarction (80%) or by haemorrhage (20%). The incidence of stroke is steady, and although mortality is decreasing, it is still a leading cause of long-term disability. Transient ischaemic attacks (TIAs) have traditionally been defined as a focal loss of brain function attributed to cerebral ischaemia that lasts less than 24 hours, although most last considerably less time than this. Causes are similar to those of ischaemic stroke, particularly atherosclerotic thromboembolism related to the cerebral circulation and cardioembolism. Diagnosis of the cause of TIAs with appropriate management is important in order to prevent a potentially devastating stroke.

Pathophysiology

Brain tissue is very sensitive to the effects of oxygen deprivation. Following cerebral vascular occlusion a series of metabolic consequences may ensue, depending on the extent, duration and vessels involved, which can lead to cell death. Reperfusion of occluded vessels may also occur, either spontaneously or via therapeutic intervention, with a potential for reperfusion injury. An area of threatened but possibly salvageable brain may surround an area of infarction. The identification of this so-called ischaemic penumbra, and therapeutic efforts to ameliorate the extent of irreversible neuronal damage, have been the subject of ongoing research efforts.

Large anterior circulation ischaemic strokes can be associated with increasing mass effect and intracranial pressure in the hours to days following onset. Secondary haemorrhage into an infarct may also occur, either spontaneously or related to therapy. Clinical deterioration often follows.

Haemorrhagic stroke

Haemorrhagic stroke is the result of vessel rupture into the surrounding intracerebral tissue or subarachnoid space. Subarachnoid haemorrhage is the subject of a separate chapter in this book (see Chapter 8.3). The neurological defect associated with an intracerebral haemorrhage is the consequence of direct brain injury, secondary occlusion of nearby vessels, reduced cerebral perfusion caused by associated raised intracranial pressure, and cerebral herniation. The causes of intracerebral haemorrhage (ICH) include:

Introduction

Patients with headache account for approximately 1% of all emergency department (ED) visits, and of these 1–4% have been demonstrated to have subarachnoid haemorrhage. Early accurate diagnosis of aneurysmal subarachnoid haemorrhage is imperative, as early occlusion of the aneurysm has been shown to reduce early complications of re-bleeding and vasospasm and improve outcome.

Pathology and epidemiology

SAH is the presence of extravasated blood within the subarachnoid space. The incidence is 5–7 per 100 000 patient-years, but is significantly higher (around 20 per 100 000) in Japan and Finland, for reasons that are unclear. Although incidence increases with age, about half of those affected are under 55, the condition being most common in the 40–60 age group. Excluding head trauma, which remains the most common cause, non-traumatic or spontaneous SAH results from rupture of a cerebral aneurysm in approximately 85% of cases, non-aneurysmal perimesencephalic haemorrhage in 10%, and the remaining 5% from other rare causes including rupture of mycotic aneurysms, intracranial arterial dissection, aterio-venous malformations, vasculities, central venous thrombosis, bleeding diatheses, tumours and drugs such as cocaine, amphetamines and anticoagulants.

Clinical features

Investigations

Imaging

A brain CT scan without contrast is the initial investigation of choice. In the first 24 hours after haemorrhage it can demonstrate the presence of subarachnoid blood in more than 95% of cases. (Fig. 8.3.1). The sensitivity, however, decreases with time owing to the rapid clearance of blood, with only 80% of scans positive at 3 days and 50% positive at 1 week. CT will also demonstrate the site and extent of the haemorrhage, indicate the possible location of the aneurysm, and demonstrate the presence of hydrocephalus and other pathological changes.

Fig. 8.3.1 Non-contrast head CT scan demonstrating widespread subarachnoid and intraventricular blood.

Magnetic resonance imaging (MRI) with FLAIR (fluid attenuated inversion recovery) is reliable in demonstrating early SAH and is superior to CT in detecting extravasated blood in the days (up to 40 days) following haemorrhage. Availability and logistical considerations make MRI impractical for use in the initial diagnostic work-up of SAH, but it may be considered in patients who present late.

CT angiography (CTA) is the preferred angiographic technique once SAH has been identified. Compared to catheter angiography it has a sensitivity of 95%, is readily available, and has a lower complication rate than catheter angiography. It should be performed as soon as the diagnosis is made. Where diagnosis has been made by CT, CTA should preferably be performed while the patient is still in the scanner. CTA is usually of sufficient quality to allow planning of endovascular or neurosurgical interventions.

Four-vessel cerebral angiography is the gold standard for confirming the presence of an aneurysm, its location and the presence of vasospasm, and was previously the preferred angiographic test. It is not, however, without risk. Neurological complications occur in ∼1.8% of cases, with re-rupture of an aneurysm reported in 2–3%. It is also less available than CTA. These factors have seen it become less favoured and used in selected cases only.

MR angiography is currently useful as a screening tool for the diagnosis of intracranial aneurysms in patients at increased risk.

In patients where SAH is present and no cause is found, then the distribution of extravasated blood on the CT scan should be reviewed. If this conforms to the perimesencephalic distribution of non-aneurysmal haemorrhage, then no repeat investigations are warranted. If, however, an aneurysmal pattern of haemorrhage is present, then a second CTA is recommended as occasionally an aneurysm may have gone undetected on the original test.

Complications

Management

The management of SAH requires general supportive measures, particularly airway protection and blood pressure control, as well as specific management of the ruptured aneurysm and the complications of aneurysmal haemorrhage.

Prognosis

SAH has a 40–60% mortality rate from the initial haemorrhage, with up to one-third of survivors having a significant neurological deficit. The most important prognostic factor is the clinical condition at the time of presentation, with coma and major neurological deficits generally being associated with a poor prognosis. Survival rates have been reported at 70% for grade I, 60% for grade II, 50% for grade III, 40% for grade IV and 10% for grade V SAH.

It is worth noting, however, that survival without brain damage is possible even after respiratory arrest. Even patients who make a good recovery may suffer cognitive and psychosocial dysfunction.

Aneurysm screening in patients who have survived aneurysmal SAH is not advocated, as although these patients are at increased risk of new or recurrent aneurysmal bleeds, screening cannot be demonstrated to be cost effective or increase quality of life.

Incidental unruptured aneurysms

If an unruptured aneurysm is found incidentally, it raises the dilemma of the risk–benefit rationale between intervention and conservative management. Factors taken into account include age, aneurysm size and location, gender, country, comorbidity and family history. Such patients should be referred to a neurosurgical service for advice and counselling.

Conclusion

Clinical suspicion of the diagnosis of SAH gained from a history of sudden, severe or atypical headache demands a full investigation, including brain CT scan and, if necessary, lumbar puncture. Once SAH has been diagnosed, urgent neurosurgical referral and management are required.

Introduction

Consciousness can be defined as a state of awareness of self and the environment. This presumes subjectivity, unity and intentionality, implying that each individual’s perception is unique, consisting of a moulding of various sensory modalities over time and interpreted within the full range of that individual’s experiences.

It is clear even from this limited description that the definition of consciousness is metaphysical and difficult to quantify. It would also include what is clinically described as mental state, but psychiatric disease and its differentiation from medical pathology is excluded from this discussion as it is discussed elsewhere.

For clinical purposes, the ability of the individual to respond appropriately to environmental stimuli provides a quantifiable definition of consciousness. Pragmatically, consciousness equals responsiveness.

Pathophysiology

The level of consciousness describes the rousability of the individual, whereas the content of consciousness may be assessed in terms of the appropriateness of the individual’s response. Broadly speaking, the first is a brainstem function and the second is an attribute of the forebrain.

The physical portions of the brain involved in consciousness consist of the ascending arousal system that begins with monoaminergic cell groups in the brain stem and culminates in extensive diffuse cortical projections throughout the cerebrum. En route there is input and modulation from both thalamic and hypothalamic nuclei, as well as basal forebrain cell groups.

The integration of the brain stem and the forebrain is illustrated by individuals who have an isolated pontine injury. They remain awake, but the intact forebrain is unable to interact with the external world, hence the aptly named ‘locked-in syndrome’. At the other end of the spectrum are individuals in a persistent vegetative state who, in spite of extensive forebrain impairment, appear awake but totally lack the content of consciousness. These clinical extremes emphasize the important role of the brain stem in modulating motor and sensory systems through its descending pathways and regulating the wakefulness of the forebrain through its ascending pathways.

Impairment of conscious state implies dysfunction of the ascending arousal system in the paramedian portion of the upper pons and midbrain, its targets in the thalamus or hypothalamus, or both cerebral hemispheres. The resultant changes in the conscious state range from awakeness through lethargy and stupor to coma with a progressively depressed response to various stimuli.

Numerous scales have been proposed to define consciousness but the one that has found universal acceptance is the Glasgow Coma (or Responsiveness) Scale (GCS) (Table 8.4.1). Initially described in 1974 for the assessment of traumatic head injuries, 25 years of experience have shown that the scale can also be used in non-traumatic situations to provide a structured assessment of an individual’s conscious state at various points in time, and also to monitor progress. Trends provided by repeated measurements of the GCS give clinicians an objective measure to monitor a patient’s deterioration or improvement in response to therapy. In quantifying and standardizing the various responses, the GCS has enabled clinicians worldwide to compare data and therapies. In the spectrum from full awareness to unrousable, coma or unconsciousness is arbitrarily defined as a GCS ≤8.

Table 8.4.1 The Glasgow Coma Scale

Introduction

The terms ‘seizure’, ‘convulsion’ and ‘fit’ are often used both interchangeably and incorrectly. A seizure is an episode of abnormal neurological function caused by an abnormal electrical discharge of brain neurons. The seizure is also referred to as an ictus or ictal period. A convulsion is an episode of excessive and abnormal motor activity. Seizures can occur without convulsions, and convulsions can be caused by other conditions. The term ‘fit’ is best avoided in medical terminology, but is a useful term for non-medical personnel.

Seizures are common. It has been estimated that up to 10% of the population will have at least one seizure in their lifetime, and 1–3% of the population will develop epilepsy.¹ A single seizure may be a reaction to an underlying disorder, part of an established epileptic disorder, or an isolated event with no associated pathology. The challenge is to rapidly identify and treat life-threatening conditions as well as to identify benign conditions that require no further investigation or treatment.

The manifestations of epileptic disorders are extremely varied. Two international classifications have been developed: the International Classification of Epileptic Seizures, and the International Classification of Epilepsy and Epileptic Syndromes.^2,3 The former divides epileptic seizures into two major categories: partial and generalized. Partial epileptic seizures are further classified according to the impairment or the preservation of consciousness into simple partial and complex partial seizures. Either condition may secondarily generalize into tonic–clonic seizures. Generalized seizures can be divided into convulsive and non-convulsive types.

Convulsive seizures are generalized tonic–clonic seizures or grand mal seizures. Non-convulsive generalized seizures include absence seizures (previously termed petit mal seizures), myoclonic, tonic and atonic seizures. Under the International Classification, epilepsy and epileptic syndromes are initially classified according to their corresponding types of seizure into localization related and generalized disorders. Each disorder can be further classified according to its relationship to aetiological or predisposing factors into symptomatic, cryptogenic or idiopathic types.³ Different seizure types are associated with differing aetiological and prognostic factors. The details of the classification systems are not as important in emergency medicine as the concept of recognizing the different seizure types and being aware of the accepted terminology when discussing and referring cases.

Given the high frequency of this condition in emergency departments (ED) it is important to have a management strategy formulated in advance. One such approach has been developed by the American College of Emergency Physicians.⁴ The four main management concepts are as follows:

First seizures

A generalized convulsion is a dramatic event. Patients and those accompanying them will often be frightened, anxious and concerned, not only for the acute event but for what it may signify. A diagnosis of epilepsy carries important implications. The patient’s occupation, social activities, ability to drive a car and long-term health implications may all be profoundly influenced. It is therefore vital that the diagnosis is correct and explained fully to the patient and relatives.

The majority of patients will have completed the seizure before arrival in the ED. Patients still seizing are treated immediately according to the guidelines below for status epilepticus.

The first and most important task is to determine whether a seizure has occurred. As the majority of patients will have returned to normal by the time they are reviewed in the ED, the diagnosis is made primarily on history. Patients will not remember seizures other than simple partial seizures, and the reports of witnesses may be unreliable or inconsistent. With the exception of partial seizures, generalized seizures are not accompanied by an aura. Most seizures last less than 2 minutes, are associated with impaired consciousness, loss of memory for the event, purposeless movements, and a period of post-ictal confusion. Although witnesses may grossly overestimate the duration, prolonged seizures, those occurring in association with a strong emotional event and those with full recall of events, should be regarded with suspicion. Similarly, motor activity that is coordinated and not bilateral, such as side-to-side head movements, pelvic thrusting, directed violence and movement that changes in response to external cues, are less likely to be true seizures.

Conditions such as syncope may be accompanied by myoclonic activity and are important to distinguish from true seizures. Migraine, transient ischaemic attacks, hyperventilation episodes and vertigo are all important conditions to consider in the differential diagnosis. Pseudoseizures will be discussed below.

The history, examination and investigation process is aimed at identifying associated conditions and treatable causes of seizures. The aetiology of seizures can be classified into five groups on this basis:

Table 8.5.1 Acute symptomatic causes of seizures

(Reproduced with permission from Brown AF, Wilkes GJ. Emergency department management of status epilepticus. Emergency Medicine 1994; 6: 49–61)

A careful history is needed to decide whether this is part of an ongoing process or an isolated event. Patients may not recall previous events, may not recognize their significance, or may even avoid reporting previous episodes for fear of being labelled ‘epileptic’, with the associated consequences. Particular attention should be paid to any history of unexplained injuries, especially when they occur during blackouts or during sleep. Any history of childhood seizures, isolated myoclonic jerks and a positive family history increases the likelihood of epilepsy.

A complete physical and neurological examination is mandatory. Evidence of alcohol and drug ingestion and head trauma is particularly important. A comprehensive medication history may include agents known to reduce the seizure threshold in susceptible individuals, e.g. tramadol, selective serotonin reuptake inhibitors.⁵ A careful mental state examination in seemingly alert patients may reveal evidence of a resolving post-ictal state or of underlying encephalopathy. All patients not fully alert should not be assumed to simply be in a post-ictal state until other causes are excluded. Of particular importance is any evidence of underlying illness, such as fever, nuchal rigidity (meningitis) or cardiac murmurs (endocarditis). Needle tracks, evidence of chronic liver disease, dysmorphic features and marks such as café-au-lait spots (neurofibromatosis) are important aetiological clues. Complications such as tongue biting, broken teeth and peripheral injuries are not uncommon in generalized seizures. Stress fractures can occur, particularly in the elderly, and posterior dislocation of the shoulder is an uncommon but significant and easily overlooked finding.

The investigations necessary following an uncomplicated seizure are minimal. Although it is common practice to order a variety of tests, such as electrolytes, blood sugar level and full blood count, these are rarely of benefit in the fully recovered patient. Elevated neutrophil counts in blood and CSF may be seen as a result of a generalized seizure in the absence of an infectious disorder. Although electrolyte abnormalities may cause seizures they are unlikely to be the cause if the patient has recovered. A serum prolactin level at 20 and 60 minutes post seizure may be helpful if the diagnosis is in doubt. Patients with an abnormal physical or neurological examination should be managed according to clinical findings and the results of laboratory and radiological investigations. Findings suggestive of meningitis, encephalitis or subarachnoid haemorrhage are indications for cranial CT scan and lumbar puncture.

There are no clear guidelines to the routine need for or urgency of neuroimaging following a single uncomplicated seizure. Patients with focal neurological signs, those who do not recover to a normal examination, and those with a history of head trauma or intracranial pathology should all undergo cranial CT as soon as possible. The dilemma arises in patients with complete recovery and no focal signs. The incidence of abnormalities on CT in this group of patients is less than 1%.⁶ The decision as to whether and when to scan patients in this group will be determined largely by local factors. Generally, a contrast CT (more sensitive for subtle lesions) is performed on an outpatient basis prior to review. MRI is more sensitive than CT for infarcts, tumours, inflammatory lesions and vascular lesions, but cost and availability limit its use as a primary investigative modality.

Electroencephalography (EEG) at the time of a seizure will make a definitive diagnosis. It is not usually performed in the acute setting except when non-convulsive activity is suspected. Typically, an EEG is obtained electively on an outpatient basis, when it may still indicate an underlying focus of activity and may be able to detect specific conditions.

Once a diagnosis of first seizure is made and intercurrent conditions are excluded or treated, the patient may be discharged home. In most cases no treatment is needed. It must be stressed to the patient that a diagnosis of epilepsy has not been made but is being considered. When the suspicion is reasonable the patient should be given the same precautionary advice as epileptic patients with regard to driving and other activities that may place them or others at risk.

The planning of investigation and follow-up for patients suspected of having a first seizure is best done in conjunction with a neurology service. Planning and consultation will ensure that appropriate investigations are completed in a timely fashion. Generally, an inter-ictal EEG and contrast CT are completed prior to review.

Status epilepticus

Status epilepticus (SE) may be defined as ‘two or more seizures without full recovery of consciousness between seizures, or recurrent epileptic seizures for more than 30 minutes’.⁷

Status epilepticus has been reported to account for 1–8% of all hospital admissions for epilepsy, 3.5% of admissions to neurological intensive care, and 0.13% of all visits to a university hospital ED. It is more common at the extremes of age, with over 50% of all cases occurring in children and a disproportionately high incidence in those over 60 years of age. SE is also more frequent in the mentally handicapped and in those with structural cerebral pathology, especially of the frontal lobes. Four to 16% of adults and 10–25% of children with known epilepsy will have at least one episode of SE. However, SE occurs most commonly in patients with no previous history of epilepsy.⁸

Many compensatory physiological changes accompany seizures. As the duration is increased these mechanisms begin to fail, with an increased risk of permanent damage. Brain damage resulting from prolonged SE is believed to be caused by excitatory amino acid neurotransmitters such as glutamate and aspartate. These lead to an influx of calcium into neuronal cytoplasm and an osmotolysis with cell destruction. Continuing seizure activity itself contributes substantially to neuronal damage, which is further exacerbated by hypoxia, hypoglycaemia, lactic acidosis and hyperpyrexia. When seizures continue for over 60 minutes, the risk of neuronal injury increases despite optimal delivery of oxygen and glucose. The longer an episode of SE continues, the more refractory to treatment it becomes, and the more likely it is to result in permanent neuronal damage. Mortality increases from 2.7% with seizure duration under 1 hour, to 32% with duration beyond this.⁸ Generalized convulsive SE is therefore a medical emergency.

Treatment of SE is along the same lines as the resuscitation of all seriously ill patients. Management is in a resuscitation area with attention to four specific factors:

Each stage of resuscitation is made more difficult by the presence of active convulsions. No attempt should be made to prise clenched teeth apart to insert an oral airway: a soft nasal airway will suffice. Oxygen should be given by tight-fitting mask and the patient positioned in the left lateral position to minimize the risk of aspiration. Intravenous access is important for drug treatment and fluid resuscitation, but may be difficult in actively seizing patients. Although SE cannot be diagnosed until seizures have persisted for 30 minutes, patients still seizing on arrival at the ED should be treated with anticonvulsants immediately.

The principal pharmacological agents used are benzodiazepines and phenytoin. The benzodiazepines used vary between countries, with little clinical evidence to support any particular one. In Australasian centres midazolam is preferred, in increments of 1–2 mg i.v. If i.v. access cannot be rapidly secured, midazolam i.m. at a dose of 0.2 mg/kg will terminate most seizures.⁹ Alternatives to midazolam are diazepam and clonazepam. Diazepam can be administered rectally if necessary, and this technique can be taught to parents with high-risk children. However, onset of action by this route in adults is slow and unpredictable. All benzodiazepines share the disadvantages of respiratory depression, hypotension, and a short duration of clinical effect.

Phenytoin is usually used as a second-line agent in a dose of 15–20 mg/kg at a rate of no more than 50 mg/min. Rapid administration is associated with bradyarrhythmias and hypotension. The common practice of administering 1 g is inadequate for most adults. The effect of phenytoin does not commence until 40% of the dose has been administered; for this reason it should be commenced at the same time that i.v. benzodiazepines are given. Most people on anticonvulsants who present in SE have negligible drug levels, and the side effects from a full loading dose on top of a therapeutic level are minimal. The full loading dose should therefore be given even when the patient is known to be on therapy.¹⁰

The most common causes of failure to control seizures are:

Causes of failure to regain consciousness following treatment of seizures include the medical consequences of SE (hypoxia, hypoglycaemia, cerebral oedema, hypotension, hyperpyrexia), sedation from antiepileptic medication, progression of the underlying disease process, non-convulsive SE and subtle generalized SE.

When benzodiazepines and phenytoin are ineffective, expert advice should be sought. Drugs that may be used in the control of SE are summarized in Table 8.5.2. Inhalational or barbiturate anaesthesia can also be used. Both require expert airway control, and in some cases inotropic support. Management in an intensive care unit is mandatory.

Table 8.5.2 Doses of drugs used in refractory SE

(Modified with permission from Brown AF, Wilkes GJ. Emergency department management of status epilepticus. Emergency Medicine 1994; 6: 49–61)

For all patients with SE, early consultation with intensive care and neurology services is essential in planning definitive management and disposition.

Non-convulsive seizures

Not all seizures are associated with convulsive activity. Convulsive seizures are generally easy to recognize, whereas non-convulsive seizures are more subtle and often require a high index of suspicion. These types of seizure are an important cause of alterations in behaviour and conscious level, and may precede or follow convulsive episodes. Seizures can involve any of the sensory modalities, vertiginous episodes, automatism, autonomic dysfunction or psychic disturbances, including déjà vu and jamais vu experiences. Non-convulsive seizures can easily be confused with migraine, cerebrovascular events or psychiatric conditions. The definitive diagnosis can only be made by EEG during the event.

Non-convulsive seizures may be partial (focal) or generalized. Complex partial seizures and focal seizures account for approximately one-third of all seizures, whereas primary generalized non-convulsive seizures (absence seizures) account for 6%.¹¹

Non-convulsive status epilepticus (NCS) accounts for at least 25% of all cases of SE and is diagnosed more frequently when actively considered. Absence seizures rarely result in complete unresponsiveness, and patients may appear relatively normal to unfamiliar observers. NCS may precede or follow convulsive seizures and may easily create the perception of a cerebral vascular or psychiatric event. The longest reported episode of absence status is 60 days, and that of complex partial status 28 days.¹²

Treatment of non-convulsive seizures in the acute setting is the same as for convulsive seizures.¹² The event is terminated with benzodiazepines in most instances, and should be followed by a search for precipitating causes. An estimated 50% of patients with simple partial seizures have abnormal CT scans.¹² Long-term seizure control uses different agents from those used for convulsive seizures, highlighting the importance of involving a neurological service when planning follow-up.¹²

Pseudoseizures

Pseudoseizures or psychogenic seizures are events simulating neurogenic seizures but without the accompanying abnormal neuronal activity. Differentiation from neurogenic seizures may be extremely difficult, even for experienced neurologists. Neurogenic and psychogenic seizures may coexist, making the diagnostic dilemma even more complex. Differentiation will often require video-EEG monitoring, but this facility is not available in the ED and other methods must be used. It is important to recognize pseudoseizures so as to prevent the possible iatrogenic consequences of unnecessary treatment, while at the same time not withholding treatment from patients with neurogenic seizures.

Pseudoseizures are more common in women, less common after 35 years of age, and rare in patients over 50.¹³ They may be associated with a conversion disorder, malingering, Munchausen syndrome or Munchausen syndrome by proxy. Patients with conversion disorder differ from malingerers by being unaware of the psychiatric cause of their actions.

Pseudoseizures typically last more than 5 minutes, compared to neurogenic seizures which usually terminate within 1–2 minutes. Multiple patterns of seizures tend to occur in individual patients, and post-ictal periods are either very brief or absent. Patients with recall of events during what appears to be a generalized convulsive seizure are likely to have had a psychogenic seizure. Extremity movement out of phase from one side to the other and head turning from side to side typify pseudoseizures. Forward pelvic thrusting occurs in 44% of patients with pseudoseizures and is highly suggestive of the diagnosis.¹⁴

Several manoeuvres are useful in identifying pseudoseizures. Eye opening and arm drop tests are accompanied by avoidance, eyes turning away from the moving examiner, and termination of the event when the mouth and nostrils are occluded are characteristic. Simple verbal suggestion and reassurance are also frequently successful.

The most definitive means of differentiating pseudoseizures is by ictal EEG or video-EEG monitoring. Unfortunately, this is of little value in the ED. Blood gas determinations demonstrate a degree of acidaemia in neurogenic tonic–clonic seizures, but not in patients with pseudoseizures. Pulse oximetry will detect a fall in SaO₂ during neurogenic but not pseudoseizures. Serum prolactin levels rise and peak 15–20 minutes after generalized tonic–clonic seizures, and then fall with a half-life of 22 minutes. The levels do not consistently rise with partial seizures, and remain normal with pseudoseizures.¹⁵

Patients presenting with pseudoseizures are often treated with anticonvulsant medications, both acutely and for maintenance. Such patients usually demonstrate resistance to anticonvulsant medication, and many will therefore present with therapeutic or supratherapeutic levels. It is difficult to resist the temptation to immediately administer pharmacotherapy when confronted with a convulsing patient, but to do so will result in patients with pseudoseizures receiving unnecessary and potentially harmful treatment.

Careful examination of eye movements, pupil reactions, asynchronous limb movements, rapid head turning from side to side, forward pelvic thrust movements, testing for avoidance manoeuvres and monitoring pulse oximetry may enable the diagnosis to be made and drug therapy avoided. In doubtful cases, blood gas determinations are helpful and serum prolactin levels can be collected for later analysis. Doubtful cases should be discussed with a neurology service and arrangements made for emergency EEG.

Once the diagnosis is confirmed it must be presented in an open and non-threatening manner. Patients often have underlying personal and/or family problems that will need to be addressed. Psychotherapy is effective, but seizures often relapse at times of stress.

Alcohol-related seizures

Seizures represent 0.7% of ED visits, and alcohol contributes to approximately 50% of these. ¹⁶ The majority of alcohol-related seizures occur as part of the alcohol withdrawal syndrome.¹⁷

Although the precise pathophysiology of alcohol-related seizures has not been elucidated, it is clear that alcohol is a direct CNS toxin with direct epileptogenic effects. Acute toxicity and withdrawal are both associated with an increased incidence of seizures. Alcohol intoxication and chronic alcohol abuse are also associated with increased incidences of intercurrent disease such as trauma, coagulopathy, falls, assaults and other drug intoxication, all of which further increase the likelihood of seizures. The management of seizures presumed to be alcohol related must include a search for associated disease and other causes.

Benzodiazepines are the principal anticonvulsant agent for acute seizures. These agents are also valuable in the treatment of withdrawal. Phenytoin is ineffective in the control of acute seizures or as a preventative.

Drug-related seizures

Seizure activity in the setting of acute drug overdose is an ominous sign associated with greatly increased mortality and morbidity. The most commonly reported are in association with cyclic antidepressants (CA), antihistamines, theophylline, isoniazid, and drugs of addiction such as cocaine and amphetamines. The diagnosis and management of these toxic syndromes are discussed in the section on toxicology.

Some medications are also associated with lowering seizure threshold in susceptible individuals. Tramadol in particular has been increasingly prescribed for analgesia in recent times and associated with new-onset seizures at normal therapeutic doses.⁵ A complete medication history is therefore essential.

Post-traumatic seizures

Post-traumatic epilepsy develops in 10–15% of serious head injury survivors.¹⁸ More than half will have their first seizure within 1 year. Significant risk factors are central parietal injury, dural penetration, hemiplegia, missile wounds and intracerebral haematomas.¹⁹ Early treatment with phenytoin for severe head injuries reduces the incidence of seizures in the first week only.²⁰

Seizures developing after significant head trauma have a higher incidence of intracranial pathology. Contrast CT is the initial investigation of choice. MRI will demonstrate more abnormalities but has not been shown to affect outcome. Long-term treatment with anticonvulsants should be planned in conjunction with a neurosurgical service.

Seizures and pregnancy

Seizures can occur during pregnancy as part of an established epileptic process, as new seizures, or induced by pregnancy. The most significant situations are eclampsia and generalized convulsive status epilepticus. At all times the management is directed at both mother and baby, with the realization that the best treatment for the baby will relate to optimal maternal care.

In previously diagnosed epileptics there is an increased risk of seizures during pregnancy of 17%.²¹ Anticonvulsant levels are influenced by reduced protein binding, increased drug binding and reduced absorption of varying degrees. The final effect on free drug levels is unpredictable and is most variable around the time of delivery.²² Careful clinical monitoring is essential, and monitoring of free drug levels rather than total serum levels may be necessary in selected patients. Anticonvulsants also interfere with the metabolism of vitamins D, K and folic acid. Supplementation is advisable.

Isolated simple seizures place both mother and fetus at increased danger of injury, but are otherwise generally well tolerated. Generalized seizures during labour cause transient fetal hypoxia and bradycardia of uncertain significance. Generalized convulsive SE is life-threatening to both mother and fetus at any stage of pregnancy.

All of the anticonvulsants cross the placenta and are potentially teratogenic. The risk of malformation in children is increased from 3.4% in the general population to 3.7% in epileptic mothers.²³ In general, the types of malformation associated are not drug specific, apart from the increased risk of neural tube defects associated with valproate and carbamazepine. Prenatal screening for such defects is advised in patients who become pregnant while taking these agents. The risk from uncontrolled seizures greatly outweighs the risk from prophylactic medication in patients with good seizure control.^3,24

The management of seizures in pregnant patients is along the same lines as for non-pregnant patients. After 20 weeks’ gestation the patient should have a wedge placed under the right hip to prevent supine hypotension, and eclampsia must be considered. Investigation will include an assessment of fetal wellbeing by heart rate, ultrasound and/or tocography, as indicated. Management and disposition should be decided in consultation with neurology and obstetric services.

Eclampsia is the occurrence of seizures in patients with pregnancy-induced toxaemia occurring after the 20th week of pregnancy, and consists of a triad of hypertension, oedema and proteinuria. One in 300 women with pre-eclampsia progresses to eclampsia. Seizures are typically brief, self-terminating, usually preceded by headache and visual disturbances, and tend to occur without warning.²⁵ Treatment is directed at controlling the seizures and hypertension, and expedient delivery of the baby. Magnesium sulphate is effective in seizure control and is associated with a better outcome for both mother and baby than standard anticonvulsant and antihypertensive therapy. ^26–29 The mechanism of action is unclear.²⁵

Management of SE in pregnancy includes consideration of eclampsia, positioning in the left lateral position, and assessment and monitoring of fetal wellbeing. Urgent control of seizures is essential for both mother and baby. Phenobarbital may reduce the incidence of intraventricular haemorrhage in premature infants, and should be considered in place of phenytoin in this circumstance.30 Early involvement of obstetric and neurology services is essential.

Future directions

Non-invasive portable modalities allowing definitive precise diagnosis of seizures in the ED will reduce the need for subsequent investigations in the majority of patients who do not have true epilepsy, and permit early focused therapy. Advances in pharmacotherapy and neurosurgical techniques will also improve seizure control with minimal side effects, allowing patients to more effectively resume normal activities.

Introduction

Syncope and vertigo are relatively common symptoms. They are often described by patients using the term ‘dizziness’; however, it is essential to differentiate between the two. Syncope and vertigo both represent a significant diagnostic challenge and it is important to risk-stratify patients accurately to distinguish between potentially life-threatening and benign causes.

Syncope

Syncope as a presenting symptom represents about 1–1.5% of all emergency department (ED) attendances.¹ It is a symptom, not a diagnosis. It is defined as a loss of consciousness induced by the temporarily insufficient flow of blood to the brain. Patients recover spontaneously, without therapeutic intervention or prolonged confusion.

There is no simple test to distinguish between the benign and the potentially life-threatening causes of syncope, but a careful history, examination and bedside investigations can help determine appropriate disposition.

The causes of syncope are summarized in Table 8.6.1. The most common cause in all age groups is neurally mediated syncope, also known as neurocardiogenic or vasovagal syncope.² Orthostatic hypotension and cardiac causes are the next most common.³

Table 8.6.1 Aetiology of syncope

Vertigo

Vertigo is defined as the disabling sensation in which the affected individual feels that he himself or his surroundings are in a state of constant movement. It has a reported 1-year incidence of 1.4%.¹⁴ Like syncope, it is a symptom not a diagnosis, and has as many causes. The difficulty is that whereas many of the causes of vertigo are benign, it may be a symptom of serious neurological conditions such as vertebrobasilar stroke.