Postural induced-tremor in psychiatry

From one to many: Hypertonia in schizophrenia spectrum psychosis an integrative review and adversarial collaboration report

Different types of resistance to passive movement, i.e. hypertonia, were described in schizophrenia spectrum disorders (SSD) long before the introduction of antipsychotics. While these have been rediscovered in antipsychotic-naïve patients and their non-affected relatives, the existence of intrinsic hypertonia vs drug-induced parkinsonism (DIP) in treated SSD remains controversial. This integrative review seeks to develop a commonly accepted framework to specify the putative clinical phenomena, highlight conflicting issues and discuss ways to challenge each hypothesis and model through adversarial collaboration. The authors agreed on a common framework inspired from systems neuroscience. Specification of DIP, locomotor paratonia (LMP) and psychomotor paratonia (PMP) identified points of disagreement. Some viewed parkinsonian rigidity to be sufficient for diagnosing DIP, while others viewed DIP as a syndrome that should include bradykinesia. Sensitivity of DIP to anticholinergic drugs and the nature of LPM and PMP were the most debated issues. It was agreed that treated SSD should be investigated first. Clinical features of the phenomena at issue could be confirmed by torque, EMG and joint angle measures that could help in challenging the selectivity of DIP to anticholinergics. LMP was modeled as the release of the reticular formation from the control of the supplementary motor area (SMA), which could be challenged by the tonic vibration reflex or acoustic startle. PMP was modeled as the release of primary motor cortex from the control of the SMA and may be informed by subclinical echopraxia. If these challenges are not met, this would put new constraints on the models and have clinical and therapeutic implications.

Movement disorders induced by psychiatric drugs that do not block dopamine receptors

Most movement disorders in psychiatric patients are induced by neuroleptic antipsychotic medications, all of which are dopamine D2 receptor blocking drugs. These include: acute onset disorders: dystonic reactions, akathisia and the neuroleptic malignant syndrome (NMS); non-acute onset parkinsonism; and the tardive syndromes. However, many other medications, when used at recommended doses, also induce movement disorders, with tremor being the most common. With the exception of serotonin syndrome, they are rarely as severe or disabling as the neuroleptic extrapyramidal syndromes may be. The serotonin reuptake inhibiting (SSRI) drugs are associated with the serotonin syndrome, a life-threatening disorder, but may also cause tremor and akathisia. While SSRI's have been thought to occasionally cause a tardive dyskinesia-like syndrome, this almost never occurs without prior or concurrent neuroleptic exposure as well. There also are few reliable data to support an association between antidepressants and parkinsonism. Valproic acid has been shown to cause parkinsonism, and lithium may as well, in addition to both having the well-known side effect of tremors. Myoclonus and asterixis are usually induced by toxic levels of medications but may appear with therapeutic levels, particularly with anticonvulsant mood stabilizers, and clozapine. Ataxia rarely occurs with non-toxic levels of drug, particularly anticonvulsants, benzodiazepines and lithium.

Risk Factors for Tremor in a Population of Patients with Severe Mental Illness: An 18-year Prospective Study in a Geographically Representative Sample (The Curacao Extrapyramidal Syndromes Study XI)

Background

The aim was to assess incidence, prevalence and risk factors of medication-induced tremor in African-Caribbean patients with severe mental illness (SMI).

Method

A prospective study of SMI patients receiving care from the only mental health service of the previous Dutch Antilles. Eight clinical assessments, over 18 years, focused on movement disorders, medication use, and resting tremor (RT) and (postural) action tremor (AT). Risk factors were modeled with logistic regression for both current (having) tremor and for tremor at the next time point (developing). The latter used a time-lagged design to assess medication changes prior to a change in tremor state.

Results

Yearly tremor incidence rate was 2.9% and mean tremor point prevalence was 18.4%. Over a third of patients displayed tremor during the study. Of the patients, 5.2% had AT with 25% of cases persisting to the next time point, while 17.1% of patients had RT of which 65.3% persisted. When tremor data were examined in individual patients, they often had periods of tremor interspersed with periods of no tremor.

Having RT was associated with age (OR=1.07 per year; 95% confidence interval 1.03–1.11), sex (OR=0.17 for males; 0.05–0.78), cocaine use (OR=10.53; 2.22–49.94), dyskinesia (OR=0.90; 0.83–0.97), and bradykinesia (OR=1.16; 1.09–1.22). Developing RT was strongly associated with previous measurement RT (OR=9.86; 3.80–25.63), with previous RT severity (OR=1.22; 1.05–1.41), and higher anticholinergic load (OR= 1.24; 1.08–1.43).

Having AT was associated with tremor-inducing medication (OR= 4.54; 1.90–10.86), cocaine use (OR=14.04; 2.38–82.96), and bradykinesia (OR=1.07; 1.01–1.15). Developing AT was associated with, previous AT severity (OR=2.62 per unit; 1.64–4.18) and tremor reducing medication (OR=0.08; 0.01–0.55).

Conclusions

Long-stay SMI patients are prone to developing tremors, which show a relapsing–remitting course. Differentiation between RT and AT is important as risk factors differ and they require different prevention and treatment strategies.

Case Studies in Tremor

Tremor is a frequent patient complaint in the neurologist's office. Nevertheless, despite the routine nature of this office presentation, misdiagnosis of common tremors is not an infrequent practice. In addition, there are less common causes of tremor that can be missed if the clinician is not aware of key features. An organized and methodical history and neurologic examination are essential in developing the differential diagnosis in tremor patients and ultimately in achieving the correct diagnosis. Awareness of key historical features associated with tremor and knowledge of the movement disorders examination will improve tremor assessment.

Adverse drug reactions induced by valproic acid

Valproic acid is a widely-used first-generation antiepileptic drug, prescribed predominantly in epilepsy and psychiatric disorders. VPA has good efficacy and pharmacoeconomic profiles, as well as a relatively favorable safety profile. However, adverse drug reactions have been reported in relation with valproic acid use, either as monotherapy or polytherapy with other antiepileptic drugs or antipsychotic drugs. This systematic review discusses valproic acid adverse drug reactions, in terms of hepatotoxicity, mitochondrial toxicity, hyperammonemic encephalopathy, hypersensitivity syndrome reactions, neurological toxicity, metabolic and endocrine adverse events, and teratogenicity.

Lithium and valproate-induced tremors

Lithium and valproate are mood stabilizers known to cause tremor. This article concisely addresses etiological questions, expected time frame of tremor onset, and treatment options for this medication-induced side effect. Along with dosage modifications of the tremor-inducing medication, authors review evidence from small trials of adjunctive treatment modalities.