Chapter. 11. Movement Disorders and Neurologic Aspects of Psychotropic Drugs
OVERVIEW
1. Acute dystonic reactions are common when starting antipsychotic chemotherapy – diphentydramine (Benadryl) 50 mg IV provides most rapid and safe relief within minutes. Alternatively, diphenhydramine may be given IM or benztropine may be given IV or IM ( 1-2 mg).
2. Parkinsonism is commonly seen, especially in the first few weeks of antipsychotic chemotherapy. There may be stiffness, reduced arm movement when walking, tremors, and sialorrhea. Prophylactic administration of an antiparkinsonian drug in low dosage 2 to 4 times daily may reduce the incidence and severity of acute extrapyramidal symptoms. These drugs should not be used prophylactically in the elderly or in patients with OBS. More potent antipsychotic agents with less anticholinergic potency are more likely to produce acute extrapyramidal (parkinsonian) effects. There is no evidence that neuroleptics with lower potential for producing acute EPS are less likely to produce the late-occurring neurologic syndrome known as tardive dyskinesia.
3. Akathisia is the most common acute EPS, and responds best to treatment with antiparkinsonian drugs (eg, trihexyphenidyl sequels 5 mg bid) or B blockers (eg, propranolol 10-20 mg tic).
4. Akinesia, which may be mistaken for schizophrenic withdrawal or depression, should be treated with antiparkinsonian drugs.
5. When improvement in psychotic symptoms is seen, gradual reduction in antipsychotic dosage should be accomplished, which will decrease extrapyramidal and other side effects and minimize the need for antiparkinsonian medications.
6. Most widely used antiparkinsonian medications exert their beneficial effect by blocking acetylcholine, and may thereby induce a toxic delirium.
7. Tricyclic antidepressants reduce neuroleptic-induced EPS; when these two classes of medication are administered simultaneously, antiparkinsonian drugs are usually unnecessary.
8. Most patients on long-term antipsychotic chemotherapy do not need long-term antiparkinsonian drugs.
9. Antipsychotic drugs should never be discontinued abruptly, since this may produce withdrawal dyskinesia, which looks exactly like tardive dyskinesia clinically, and will gradually disappear with slow dosage reduction and eventual discontinuation of antipsychotic drug therapy.
10. Patients receiving fluphenazine or haloperidol decanoate may require antiparkinsonian medication for three to five days starting on the second or third day after each injection as the neuroleptic blood level is approaching its peak concentration.
11. All currently used neuroleptic drugs may produce tardive dyskinesia in approximately 20% of patients receiving prolonged treatment. Lower doses or short-term administration may reduce the risk. Tardive dyskinesia will often diminish and disappear after a prolonged neuroleptic-free interval. Clonidine, clozapine, cholinesterase inhibitors. and cholinergic precursors are often useful in the treatment of tardive dyskhlesia.
12. Movement disorders due to abnormal neurotransmission: Torsion dystonia, which may be mistaken for a conversion reaction, should be treated with high-dose trihexyphenidyl, carbamazepine, and baclofen. Parkinson’s disease patients are often depressed, commonly develop dementia, and not infrequently become acutely psychotic in response to levodopa and other therapies. Judicious use of psychotropic drugs can benefit these patients.