The above discussion would suggest that taking a history from patients with headache is easy. Unfortunately this is not always the case. The CT scan in Figure 9.2 is from a patient who was incapable of giving a detailed history because of the cognitive impairment resulting from the hydrocephalus. The patient complained of vague headache, non-descript blurring of vision and a change in her personality (her sister’s psychiatrist had diagnosed schizophrenia when her sister told him about her symptoms). The two clues to the underlying diagnosis were the fact that her legs gave way when her brother hugged her (this would have increased intrathoracic and intracranial pressure) and the presence of papilloedema when examined.

FIGURE 9.2 A CT scan of the brain demonstrating a large dermoid cyst (straight arrow) with secondary hydrocephalus (dotted arrow)

Do not diagnose a psychiatric problem because of your inability to obtain a history that makes sense. This could reflect cognitive impairment as a result of the underlying disease process.

There are many different ways to approach patients with headache. The International Headache Society classification is into primary and secondary headache. In clinical practice when evaluating patients with headache there are three broad categories based on the rapidity of onset of the headache (see Figure 9.3).

FIGURE 9.3 The three broad categories of headache. ICH = intracerebral haemorrhage

The remainder of this chapter will initially discuss the approach to patients presenting with a single headache, followed by the approach to patients with recurrent headaches.

A SINGLE (OR THE FIRST) EPISODE OF HEADACHE

Sudden onset ‘thunderclap headache’

• Intracranial haemorrhage

• Subarachnoid haemorrhage

• Intracerebral haemorrhage

• Intraventricular haemorrhage

• Cough headache

• Exertional headache

• Benign sex headache

• Ice-cream headache

• Ice-pick headache

All these conditions have one thing in common and that is the sudden onset of severe headache. (The slight exception is the headache related to exertion or orgasm; see below.) What differentiates one from the other are the associated symptoms, the duration of the headache and, to a lesser extent, the circumstances under which the headache occurs. It is important to remember that the most lethal condition NOT to miss is a subarachnoid haemorrhage (SAH) and that it can occur under any circumstances including when patients exert themselves, cough, sneeze or during sexual intercourse. There are extremely rare causes of sudden severe headache such as hydrocephalic attack with or without the presence of a third ventricular colloid cyst acting as a ball valve, and very rarely sudden onset headache may be the presenting symptom of aseptic or viral meningitis [15].

INTRACRANIAL HAEMORRHAGE

Subarachnoid haemorrhage (SAH): The single most important, although probably not the commonest, cause of sudden severe headache is SAH. SAH accounts for a little over 10% of patients presenting with sudden onset ‘thunder clap’ headache [15]. A minor bleed causing sudden headache may be the only warning of a subsequent severe and often fatal haemorrhage. If the haemorrhage also occurs into the parenchyma of the brain, there may be focal neurological symptoms. Patients often describe it as the worst headache of their life [16].

The headache of SAH is occipital or generalised and of sudden onset, reaching maximum severity within seconds. If the haemorrhage is of sufficient severity, there may be transient loss of consciousness or coma induced; this occurs in nearly 50% of patients [17]. There is severe nausea, vomiting, photophobia and neck stiffness from the moment of onset of the headache. Seizures may occur. The patient is obtunded and looks extremely ill. Photopsia is NOT a feature.

Clinical features do not always clearly distinguish other causes of headache from SAH [15, 18]. The presence or lack of accompanying symptoms like nausea, vomiting, photophobia and collapse at onset does not seem a reliable means of distinguishing between SAH and benign causes of acute headache [15].

The moment the possibility of SAH is entertained, all patients should be thoroughly investigated with imaging and, if negative, a lumbar puncture (LP).

In almost 20–40% of patients with SAH a warning leak (minor haemorrhage) may occur 1–8 weeks prior to a major SAH. The associated headache (referred to as a sentinel headache) is often short-lived and the patient may not seek immediate medical attention [19]. Even if the patient consults a physician the headache seems so trivial that often the diagnosis is missed [20]. Some of these patients are seen some days to weeks later [21] with the story of a sudden, explosive severe headache, usually in the absence of any other symptoms. The briefer the headache, the less likely it was related to a warning bleed. Here the question arises as to whether they have suffered a SAH and how extensively they should be investigated, and there is no easy answer to this question.

The probability of detecting an aneurysmal haemorrhage on CT scans performed at various intervals after the ictus is [9]:

• 3 weeks, almost nil.

The probability of detecting xanthochromia with spectrophotometry of the CSF at various times after a SAH is [9]:

Magnetic resonance angiography will detect aneurysms of > 3 mm in diameter and is recommended in patients with thunderclap headache with a low index of suspicion for SAH (normal CT scan and CSF) [9], as the risk of subsequent SAH is negligible [21, 22]. If the index of suspicion for SAH is high standard angiography should be performed.

Sudden severe headache should be assumed to be due to SAH until proven otherwise.

A 3rd nerve palsy with a dilated pupil is a classic sign of a sentinel bleed.

Intracerebral haemorrhage: The headache of intracerebral haemorrhage is associated with nausea and vomiting due to raised intracranial pressure. It is often sudden in onset and of maximum severity at onset; however, it can increase in severity more slowly over a period of minutes to hours. In this situation the patient will usually have depression of the conscious state and often focal neurological signs.

Intraventricular haemorrhage: Primary intraventricular haemorrhage is rare and usually results from parenchymal (intracerebral) haemorrhage rupturing into the ventricle. The headache is of sudden onset and maximum intensity within seconds; it is usually associated with nausea, vomiting, photophobia and neck rigidity. If the haemorrhage is more severe or if it leads to secondary hydrocephalus, depression of the conscious state will occur. There are no focal neurological symptoms unless the intraventricular haemorrhage is secondary to a parenchymal haemorrhage.

COUGH, BENIGN EXERTIONAL, BENIGN SEX, ICE-CREAM AND ICE-PICK HEADACHEs

Although these headaches have a tendency to recur, they have one thing in common and that is the headache is of sudden onset and therefore they are discussed in this section.

Anybody who has suffered from a headache knows that coughing, sneezing or straining momentarily exacerbates the headache. Headache precipitated by coughing is referred to as cough headache. A similar headache can also be precipitated by anything that increases intrathoracic pressure such as sneezing, straining, laughing or stooping [24]. In the majority of patients with this headache, no structural pathology is present, although in as many as 25% it may be symptomatic (indicating the presence of an underlying pathology) with a significant proportion related to a Chiari malformation [25].

Cough headache: Benign cough headache is a headache precipitated by coughing in the absence of any intracranial disorder. The headache is of maximum severity at onset, coming on within seconds of coughing, sneezing or straining. It is very brief, lasting only a few seconds to less than a minute. There are no associated symptoms. The headache is generalised, frontal or occipital. The headaches usually resolve within 1 or 2 years although cases have been described lasting up to 12 years [26].

TREATMENT of BENIGN COUGH HEADACHE

In general reassurance only is required. Occasionally symptomatic relief can be provided with indomethacin or other non-steroidal anti-inflammatory drugs [26, 27].

Exertional headache: Benign exertional headache is a bilateral, throbbing headache, lasting from 5 minutes to 24 hours specifically provoked by physical exercise and not associated with any systemic or intracranial disorder [28]. A small percentage of patients with exertional headache may have structural pathology [28]. This headache is of sudden onset (but not usually described as explosive in nature), generalised frontal or occipital and precipitated by activities such as weight lifting or any other activity that causes the patient to Valsalva. Similar to coital headache, there may be an antecedent dull occipital pain that builds up in severity over seconds to minutes as the intensity of the exercise increases and, if the person stops exerting themselves, this warning headache will resolve and they will not experience the sudden severe headache. The aetiology of this headache is unknown. Recurrent episodes may occur for weeks, occasionally months.

Benign sex (orgasmic or coital) headache: ‘Headache associated with sexual activity’ describes bilateral headaches precipitated by masturbation or coitus in the absence of any intracranial disorder [29, 30]. The headache is sudden in onset and excruciatingly severe, occurring at the moment of orgasm. It is predominantly occipital, but may be frontal or generalised. It is brief, lasting minutes, rarely hours. There are no associated symptoms. There is often a valuable clue that is not seen with SAH: the patient may experience a dull pain in the occipital or suboccipital region that increases in severity as excitement increases, subsides if they interrupt sexual activity and recurs if they become aroused again. If the patient interrupts sexual activity and avoids orgasm, this dull headache subsides without the subsequent severe explosive headache. If you can obtain a history of this headache preceding the sudden explosive headache, then the diagnosis is quite straightforward. On the other hand, if the history of this warning headache is not elicited, the major differential diagnosis, particularly if the headache lasts hours, is SAH. The aetiology of this headache is unclear but it is almost invariably seen in patients who are experiencing considerable stress in their lives and, once the stress resolves, so do the headaches.

Rarely, patients may experience their first SAH when coughing, sneezing, straining, exerting themselves or during sexual intercourse [25]. Here, although the headache will be explosive in onset, there will not be an antecedent warning headache in the seconds before the explosive headache, and the headache will persist for hours to days and is usually associated with nausea, vomiting, neck stiffness and possibly a focal neurological deficit and/or depression of the conscious state.

TREATMENT of COUGH, EXERTIONAL AND BENIGN SEX HEADACHE

The most important aspect of the management of cough, exertional and benign sex headaches is to reassure the patient of their benign nature and to advise them that they will resolve with the passage of time. Cough, exertional and benign sex headaches may be helped by the introduction of indomethacin 25–100 mg per day, other non-steroidal anti-inflammatory drugs or a beta-blocker.

Ice-cream or cold-induced headache: Cold-induced headache occurs when the patient is eating or drinking something very cold such as ice cream that touches the palate or posterior pharyngeal wall. The patient experiences the onset over seconds of an excruciating, unilateral frontal headache that can be so severe that it may induce a profound bradycardia and syncope. This is a common cause of headache in adolescents [31] and is not influenced by eating ice cream more slowly [32].

Ice-pick headache: Ice-pick headache is also termed ‘jabs and jolts’ and refers to a curious entity in which the patient experiences recurrent, brief stabbing pains, often localised to one part of the head, rarely in other parts of the body. The patient describes the pain as lancinating like a needle, a nail or an ice pick being stabbed into their scalp. The pain lasts seconds only, may occur as a single jab of pain or there may be many stabs of pain within seconds to a minute. The commonest site is the temples. The same site on the opposite side (mirror image) of the head may be similarly affected. Ice-pick headaches occur more commonly in patients with migraine, where they can occur during or before the migraine [33]. They are benign and do not represent any sinister underlying pathology; reassurance is all that is required.

Aseptic or viral meningitis: Very rarely, aseptic or viral meningitis may present with the very abrupt onset of severe headache [15]. The associated fever and sweats and the presence of an antecedent upper respiratory tract infection provide clues to the possible diagnosis, but a lumbar puncture may be required to differentiate aseptic meningitis from SAH.

Posture-induced headache

Severe headache on standing that resolves with lying flat is characteristic of a reduced cerebrospinal fluid (CSF) pressure. This most often occurs after a lumbar puncture but may develop with a CSF leak, the so-called spontaneous low-pressure headache.

POST-LUMBAR PUNCTURE HEADACHE

The characteristic and pathognomonic feature is a headache that worsens within 15 minutes of standing and resolves within 30 minutes if the patient lies completely flat [8], particularly if the foot of the bed or the legs are elevated. If the patient lies down on several pillows the headache will be less severe but will not be abolished. It is important that the headache resolves as all headaches are usually less severe when a patient lies down. The headache can be dull or throbbing, frontal, occipital or generalised, worsened by coughing, sneezing and straining, i.e. non-specific features.

There is often neck discomfort; other associated symptoms include a change in hearing (hyperacusis), nausea, blurred vision, photophobia, horizontal diplopia, occasionally facial numbness, cognitive abnormalities and even coma. All these symptoms resolve when the patient lies completely flat.

The headache usually develops within 1 or 2 days of the lumbar puncture (LP) or epidural, although rare cases occurring 12 days later have been reported [34]. CSF pressures, by definition, are quite low and can be measured to confirm the diagnosis [35]. Although it usually resolves spontaneously, there are reports of it persisting for up to 19 months [36].

Post-LP headache occurs in as many as 30% of patients [37]. The incidence is reduced to as low as 5% when a smaller gauge needle is used, inserting the bevel parallel rather than at right angles to the fibres of the dura, the stylet is re-inserted before removing the needle or non-cutting (pencil-point) needles are used [38, 39]. There is no evidence that bedrest following an LP reduces the incidence of headache. The incidence is also not influenced by whether the LP is performed in the sitting or lying position or whether increased oral or IV fluids are administered. The volume of CSF removed does not increase the incidence of post-LP headache, thus there should be no hesitation in removing copious amounts of CSF for diagnostic purposes.

LOW-PRESSURE HEADACHE OR SPONTANEOUS INTRACRANIAL HYPOTENSION

The clinical features are identical to the headache seen after an LP. This headache relates to a leak of CSF either from the nose following a head injury (rarely a spontaneous leak) or, in the majority of patients, the leak is at the level of the spine, particularly the thoracic spine and cervicothoracic junction [35].

INVESTIGATION AND TREATMENT of LOW-PRESSURE AND POST-LP HEADACHE

Typical imaging findings consist of subdural fluid collections, pachymeningeal enhancement, pituitary hyperaemia and brain sagging on CT scans. MRI may be normal. Myelography or CSF isotope studies can often identify the CSF leak [35, 40] but are not necessary to make the diagnosis. Radioisotope cisternography typically shows absence of activity over the cerebral convexities, even at 24 or 48 hours, and early appearance of activity in the kidneys and urinary bladder.

Initial treatment is effective in as many as 85% of patients [41] and consists of lying the patient completely flat with the foot of the bed elevated, copious fluids (unproven benefit) and, if this fails, an epidural blood patch is often effective [42]. Occasionally more than one epidural blood patch may be required [43], up to as long as 19 months after the onset [36].