Neurology and psychiatry

Published on 10/04/2015 by admin

Filed under Neurology

Last modified 22/04/2025

Print this page

This article have been viewed 1455 times

Neurology and psychiatry

A primary psychiatric diagnosis is present in 13–27% of new neurology outpatients and evidence of psychiatric morbidity in up to 48%.

Introduction

A psychiatric dimension is common in neurological consultations. Neurological and psychiatric illness may be related in several ways:

Neurological diseases may have psychiatric complications.

Neurological diseases may present with psychiatric symptoms.

Psychiatric illness may present with neurological symptoms. Examples are depression presenting as pseudodementia (p. 55) and non-organic neurological illness (p. 116).

The treatments for psychiatric illnesses can cause neurological complications and vice versa. Drugs of abuse also have neurological and psychiatric complications.

Psychiatric factors may be important in triggering physical diseases, especially those to which the individual has a predisposition, e.g. epileptic seizures or migraine.

Psychiatric complications of neurological disease

Psychiatric complications of neurological disease may be reactive – a response to the handicap of the disease – or a primary manifestation of the disease itself. In some cases, both mechanisms may be active.

Anxiety

Anxiety is a common occurrence in neurology outpatients, found in 25–35%.

Depression

Depression is a common complication, and occurs especially frequently in certain diseases: Parkinson’s disease 50%, Alzheimer’s disease 30%, multiple sclerosis 25%, epilepsy 38%, stroke 25% and following head injury 25%. Depression leads to suicide in 6% of patients with Huntington’s disease, and in epilepsy the suicide risk is 5–25 times that of the general population.

Obsessive-compulsive disorder

This is also seen in movement, especially Parkinson’s disease and Huntington’s disease.

Euphoria

Euphoria, much vaunted, occurs in only 3% of patients with multiple sclerosis. Emotional lability may also be seen as part of pseudobulbar palsy, usually in multiple sclerosis, cerebrovascular disease or motor neurone disease. Pathological laughter or crying (the act without the underlying emotion) may also occur and usually relates to thalamic or brain stem disease.

Delusions

Delusions and other psychotic symptoms are seen in patients with Alzheimer’s disease, vascular dementia, focal epilepsy, multiple sclerosis, treated Parkinson’s disease and post-traumatic brain injury.

Complications of epilepsy

Epilepsy is associated with three patterns of psychotic disorder, best defined by the timing of psychotic symptoms in relation to epileptic seizures. They usually occur in patients with focal epilepsy syndromes and with known epilepsy, but occasionally may be a first presentation:

1. Postictal psychosis. Florid psychotic symptoms follow on from a flurry of severe seizures with a consistent time interval, usually 1–7 days. The episode is usually self-limiting within a week, but may require antipsychotic treatment during that time.

2. Ictal psychosis. Psychotic symptoms occur during the epileptic activity itself, usually as a manifestation of non-convulsive status epilepticus, and there is evidence of altered awareness. Patients may be agitated and hit out, but directed aggression is exceptionally rare. In both these situations, the best treatment of psychosis is to prevent seizures with antiepileptic therapy.

3. Interictal psychosis. Timing bears no relationship to identifiable epileptic seizures. Occurs more often in those with structural lesions (23%) than in mesial temporal sclerosis (5%) and is occasionally caused by antiepileptic drug therapy.

Neurological diseases presenting with psychiatric manifestations

The diagnosis of a primary psychiatric illness requires that the symptoms occur in normal consciousness. The presence of altered consciousness or periods of drowsiness suggest a neurological cause (pp. 50, 52). There may, however, be no obvious clouding of consciousness in the early stages and other factors may be helpful in making the diagnosis (Table 1).

Table 1 Comparison of organic brain syndromes and psychiatric disease

Symptom	Organic disease	Psychiatric disease
Clouding of consciousness	Common	Rare
Seizures	Common	Rare
Memory	Impaired	Often preserved
Visual hallucinations	Commonly without auditory hallucinations	Rare without auditory hallucinations
Tactile hallucinations	Commonly without auditory hallucinations	Rare without auditory hallucinations
Focal neurological signs	Sometimes	Rare
Disturbed sleep	Reversal of sleep cycle	Insomnia
Paranoia	Common	Common
Feelings of control	Rare	Sometimes
Headache	Sometimes	Sometimes

Anxiety is seen in metabolic encephalopathies, including hypoxia, thyrotoxicosis, delirium tremens and other drug-induced states. This may progress to a frank psychotic state.

Frontal lobe disorders often present with psychiatric effects. The aetiology is usually a tumour, infarction, trauma, hydrocephalus, encephalitis or focal dementia. There may be release of primitive reflexes: pout, grasp and palmar-mental reflexes. If the lesion extends more posteriorly, there may be more easily identified focal signs: hemiparesis and non-fluent dysphasia in the dominant hemisphere. There are three recognizable syndromes:

1. Disinhibition, with insomnia, hypomanic features and sometimes hypersexuality, is seen in orbitofrontal lesions.

2. Apathy, with paucity of speech and motor activity, is seen in mesial frontal lesions, especially bilateral infarction of the anterior cerebral artery. Bilateral medial thalamic lesions may produce the same syndrome. There may be urinary incontinence without warning and a gait disorder.

3. Impairment of executive function is seen in lateral convexity lesions. These patients find it difficult to maintain attention or to transfer attention from one task to the next. Despite adequate memory function, these patients perform poorly in everyday life.

Auditory hallucinations are common in psychiatric disease and may be accompanied by hallucinations in other modalities, but in organic disease these commonly occur without auditory hallucinations. Visual hallucinations most commonly occur in acute confusional states, where they are often complex (pink elephants in delirium tremens). They may also occur with lesions at any level of the visual system from the eyes to the association cortex, when they may be flashes of light or complex images and may be restricted to an abnormal visual field. Brief, stereotyped images may represent partial seizures but are also seen by normal individuals when falling off to sleep (hypnagogic hallucinations) and, rarely, in brain stem lesions (peduncular hallucinosis). Cortical Lewy body disease causes dementia with visual hallucinations in up to 85% of cases and Parkinson’s disease causes nightmares and similar hallucinations when treated with high doses of levodopa. Olfactory, gustatory and somatosensory (crawling ants on the skin) hallucinations also occur in acute organic brain syndromes and in epilepsy (p. 74).

Neurological and psychotropic medication

Drugs used in the treatment of psychiatric illness often have neurological side effects and vice versa. Withdrawal of the culprit may not be possible; Table 2 lists some alternative strategies.

Table 2 Problems with medications used in neurology and psychiatry

Antipsychotic and antiparkinsonian medication

Drugs used in the treatment of Parkinson’s disease are dopaminergic agonists, whereas those used in the treatment of psychosis are predominantly dopaminergic antagonists. While there are several different types of dopamine receptors, allowing some selectivity of action, major side effects of neuroleptic drugs are movement disorders, which may be acute (oculogyric crisis, neuroleptic malignant syndrome) or chronic (tardive movement disorders), whereas the antiparkinsonian drugs cause confusions, hallucinations and psychosis.

Neuroleptic malignant syndrome

Neuroleptic malignant syndrome (NMS) is a life-threatening complication of neuroleptic drugs. The characteristic features are muscle rigidity of an extrapyramidal type, altered consciousness and autonomic disturbance, especially hyperpyrexia, which usually develop acutely. It occurs in up to 1% of individuals receiving neuroleptic medication and may occur at any stage during treatment. The differential diagnosis includes amfetamine or MDMA (ecstasy) abuse, encephalitis, Wilson’s disease and primary catatonic schizophrenic psychosis, which are much rarer. NMS may be associated with an elevation of the creatine kinase from muscle damage but there are no diagnostic tests.

The diagnosis is made by exclusion of other causes in the appropriate context of neuroleptic therapy. Treatment is supportive with fluid replacement. Some use intravenous dantrolene sodium or bromocriptine to reduce rigidity. Major complications are renal failure secondary to dehydration, and myoglobinaemia and secondary infection. If the patient can be supported satisfactorily for 10–14 days, there are usually no sequelae and neuroleptics have been restarted in some individuals without recurrence.

Neuropsychiatric complications of drugs of abuse

Drug dependence is a psychiatric disorder, with organic components, physical dependence and tolerance, psychological components and psychological dependence. Most drugs are associated with both neurological and psychiatric complications (Table 3).

Table 3 Neuropsychiatric effects of drugs of abuse

Drug	Neurological complications	Psychiatric complications
Alcohol	Intoxication, stupor and coma, Wernicke’s encephalopathy, Korsakoff syndrome, seizures, delirium tremens, myopathy, neuropathy, cerebellar syndrome	Acute and chronic auditory hallucinosis, personality disintegration, morbid jealousy
Amfetamine	Organic hallucinosis, NMS-type syndrome, cerebral vasculitis	Chronic psychosis
MDMA (ecstasy)	Organic hallucinosis, NMS-type syndrome, destruction of serotonergic fibres	Not yet established
Cocaine	Organic hallucinosis, stroke (common), subarachnoid and cerebral haemorrhage	Depression, mania, phobic disorders, anxiety disorders
Lysergic acid (LSD)	Organic hallucinosis	Chronic psychosis, hallucinatory flashbacks

NMS, neuroleptic malignant syndrome

Neurology and psychiatry

In acute psychiatric disorders, drowsiness is a cardinal sign of a physical cause.

Neurological causes of acute psychiatric symptoms are similar to those for confusion.

Neurological causes of acute psychiatric symptoms are similar to those for dementia.

Treatments for neurological conditions often have psychiatric adverse effects and vice versa.

Related

Neurology An Illustrated Colour Text