324 Chapter 38
drugs, such as benzhexol, prophylactically to prevent extrapyramidal reac-
tions. The antimuscarinic can be withdrawn after about six weeks because
it is rarely needed beyond that time and often does more long-term harm
than good. Clozapine is an atypical neuroleptic that can be very useful
in the treatment of resistant schizophrenia, but that is not much used
otherwise because it can cause blood dyscrasias, especially in children.
The Neuroleptic Malignant Syndrome is an uncommon but potentially
fatal hazard. The four cardinal features of the full syndrome are pyrexia,
muscular rigidity, mental changes, such as mild confusion, and evidence
of autonomic dysfunction, for example, pallor, sweating or shivering.
Blood tests may show raised creatinine phosphokinase and a high white
count. Since the early symptoms can progress in less than 48 hours to
hyperpyrexia, rigidity, circulatory collapse and multiple organ failure, it
is obviously essential to monitor carefully any child or adolescent who
develops suspicious symptoms while on neuroleptics, discontinuing the
medication immediately if suspicions seem to be confirmed. The full
syndrome requires intensive care and muscle relaxants.
Long-term treatment with neuroleptics can lead to the eventual emer-
gence of dyskinesias, which may be irreversible even if medication is
stopped. The risk of these tardive dyskinesias is related to the lifetime dose,
and may be further increased if antimuscarinics have also been adminis-
tered for long periods. There is little evidence for the frequent assertion
that neurological damage also increases the risk of tardive dyskinesias.
Lithium
This is widely used for the treatment and prophylaxis of bipolar affective
disorder in adults, and may be of similar value in children and adolescents,
though the evidence is suggestive rather than conclusive. Lithium may
possibly also have a role in the treatment of severe outbursts of aggression
that are triggered by minimal provocation and that have been resistant
to appropriate psychological management. Lithium dosage is adjusted to
obtain a plasma level of around 0.7–1.0 mmol/litre on samples obtained
12 hours after the most recent dose. Common side effects include nausea,
fine tremor, thirst, polyuria and enuresis. Since there is a risk of hypothy-
roidism, thyroid function tests should be carried out before and during
treatment. Routine monitoring of renal function is probably unnecessary.
Excessive dosage leads to potentially fatal toxicity. The common early
signs are coarse tremor, worsening gastrointestinal disturbance and mild
confusion. Since these warning signs of toxicity may be less prominent in
those with intellectual disability, lithium needs to be used with particular
caution in this group.
Antiepileptic medications as psychotropics
Carbamazepine, valproate or lamotrigine can be used instead of lithium
to prevent recurrences of bipolar affective disorder, though the evidence
is weak and there is a risk of serious adverse effects, for example, hepatic
failure and pancreatitis with valproate and toxic epidermal necrolysis with