Medication-induced Movement
Disorders
Perhaps the
most uncomfortable side effects from psychotropic medications (especially
antipsychotics or neuroleptics) are the acute and chronic movement disorders.
Any psychiatrist in clini-cal practice has witnessed the intense distress that
medication-induced movement disorders may bring to patients. Perhaps most
disturbing is that unlike other medications, antipsychotics can produce
“tardive” or late-occurring movement disorders that may be persistent or even
irreversible. Patients in whom movement dis-orders develop may have more than
subjective distress; they may suffer psychosocial embarrassment that makes them
avoid being seen in public, and they may even suffer occupational impairment in
severe cases. The responsibility this places on the prescribing psychiatrist is
significant. Careful and reasoned thought must go into the analysis of whether
the benefit of treatment with a medi-cation exceeds the risk to the patient.
This includes adequately explaining and obtaining informed consent from
patients.
When a psychiatrist
prescribes a medication that has the potential to induce a movement disorder,
the physician–patient relationship is of paramount importance. Patients who
require these medications are sometimes not amenable to trusting rela-tionships
(i.e., the paranoid patient). Working with a patient who has a psychotic
illness requires that the psychiatrist establish a strong therapeutic bond with
the patient.
Approximately
5 years after chlorpromazine was observed to be effective for psychotic
disorders, orobuccal dyskinesias after pro-longed exposure to chlorpromazine
were noted. This condition lasted nearly 3 months after the medication was
stopped. This was in marked contrast to the parkinsonism-like EPS that had been
previously described to reverse on discontinuation of antipsychotics. The term tardive dyskinesia (TD) was first used
in the 1960s to de-scribe this condition. The number of reports grew rapidly in
a period of years, and many of the cases were reported to be irreversible.
There are
different types of movement disorders that may result from treatment with
psychotropic (especially neuroleptic) medica-tions. They can generally be
divided into those that occur acutely or subacutely and those that occur late in
treatment (tardive). For the purpose of this discussion, we group the movement
disorders into the relatively acute neuroleptic-induced disorders (acute
dystonia, parkinsonism, and akathisia) neuroleptic-induced TD and neurolep-tic
malignant syndrome (NMS). We also devote a section to the dis-cussion of
medication-induced postural tremor that predominantly focuses on
lithium-induced tremor. This covers the major diagnostic groupings contained
within the Diagnostic and Statistical
Manual of Mental Disorders,
Fourth Edition, Text Revision (DSM-IV-TR)
under the general title medication-induced movement disorders.
A time
line for the emergence of the neuroleptic-induced movement disorders is
provided in Table 64.1.
In
general, the more a patient is able to understand the nature of his or her
illness and the reason that a particular medication is being prescribed, the
more likely he or she is to be adherent. When the psychiatrist does not devote
adequate time to inform-ing and instructing the patient, the result may be poor
trust, poor communication and possible legal difficulties for everyone
in-volved. Unless declared incompetent by a court of law, a patient is
considered to be legally competent to consent to or refuse psy-chotropic
medications. The only exception to this rule is when an emergency situation
exists and a patient must be medicated to prevent harm to self or others. The
psychiatrist must provide information to the patient or the patient’s
decision-maker about the nature and purpose of the medication, its risks and
benefits, alternatives to the proposed treatment, and prognosis without
treatment. Obtaining a written informed consent is one way of documenting the
consent process. Another way is noting in the chart a summary of the discussion
with a patient (or caregiver) about the consent to neuroleptic treatment.
Although the antipsychotics can produce unpleasant side effects, a patient who has been prepared openly and honestly for their possibility is more likely to view the side effects as evidence of the psychiatrist’s excellent fund of knowledge rather than as a terrible surprise thrust on him or her by a dishonest or ignorant physician. On a final note, it may not be assumed that a patient already receiving antipsychotics prescribed by another physician has received an adequate informed consent. The process must be-gin anew with the new treating physician. A new twist in the legal issues surrounding antipsychotic agents is the lower incidence of EPS and TD with atypical agents. The question of what is standard of care and how this relates to patients’ prescribed conventional antipsychotics who are at a higher risk of developing a movement disorder such as TD presents interesting legal issues.
In general, the literature continues to expand with trials demonstrating reduced incidence of new onset neuroleptic-induced movement disorders with atypical antipsychotics and at least partial improvement of existing movement dis-orders caused by conventional antipsychotics. While atypical antipsychotics are not without a risk of movement disorders, the improved motor side-effect profile of the atypical agents provides a compelling argument for the use of atypical an-tipsychotics when initiating therapy, especially in susceptible populations such as the elderly. Switching to an atypical agent should be considered for those patients maintained on a con-ventional agent who develop or have a high risk of movement disorders.
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