Physiological characteristics of tremor after chronic lithium therapy

Lithium tremor revisited: pathophysiology and treatment

OBJECTIVE

Tremor occurs frequently as a side-effect of lithium, and it is, however, easily overlooked in the clinical setting. In this article, we attempt to review the pathophysiology and the clinical approach of lithium tremor.

METHOD

We searched the Pubmed and Cochrane Library for relevant articles up to the year 2012. Sixty-four articles including 10 review papers, 3 clinical trials, and 12 case reports were reviewed.

RESULTS

Lithium tremor is classified as a postural tremor and subcategorized as an exaggerated physiologic tremor. Differential diagnosis includes metabolic abnormalities, benign essential tremor, Parkinson's disease, and lithium toxicity. Various methods of evaluating lithium tremor and treatment options are discussed.

CONCLUSION

When lithium tremor has developed, thorough history taking, physical examination, and blood examination including serum lithium level are needed. Pharmacotherapy is indicated only in patients with disabling tremor.

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.

Lithium-induced tremor treated with vitamin B6: a preliminary case series

OBJECTIVE

The occurrence of tremor in patients receiving lithium is well known, but the management of this side effect is a significant problem both for patients and physicians. Although some reports have suggested that beta-blockers may be useful in treating lithium-induced tremor (LT), these agents have different side effects which limit the possibility of their use. Vitamin B6 has been reported to be effective in treatment of patients suffering from different kinds of neuroleptic-induced movement disorders including parkinsonism and tardive dyskinesia.

METHODS

This report presents the results of a preliminary four-week open-label clinical trial of five patients who suffered from LT and who were treated with vitamin B6 (900-1200 mg/d). The severity of tremor was assessed using the tremor subscale from the Simpson-Angus Scale (SAS) and Subjective Clinical Improvement Impression scale (SCII).

RESULTS

After the addition of vitamin B6 to their treatment, according to the SAS scores four patients showed an impressive improvement until total disappearance of tremor. The subjective scale, on which the patients' scored their impression of clinical improvement, showed similar results. None of the patients suffered from any side effects attributable to vitamin B6.

CONCLUSIONS

The results suggest that vitamin B6 may alleviate LT, double-blind controlled trials are needed to establish this effect.

Lithium side effects in relation to brain lithium concentration measured by lithium-7 magnetic resonance spectroscopy

1. The relationship between lithium (Li) side effects and brain Li concentration was examined in 17 patients with bipolar disorder treated with Li and other psychotropic drugs. 2. Brain Li concentration was measured by Li-7 magnetic resonance spectroscopy (MRS). Side effects were assessed using the UCLA General Side Effect Rating Scale For Lithium Treatment (GSE). 3. There was no correlation between the total GSE score and the brain, serum, or erythrocyte Li concentrations. Patients with hand tremor had significantly higher brain Li level (0.51 + or - 0.27 mM) than those without apparent tremor (0.36 + or - 0.20 mM), but no significant difference in serum Li level was seen. As far as the patients had hand tremor, they rarely had brain Li concentration less than the therapeutic range (1 of 15 measurement). On the other hand, they often had brain Li levels less than the therapeutic range when they did not have apparent tremor (13 of 52 measurements). 4. This preliminary study suggests that hand tremor is associated with the brain Li concentration.

Acute lithium-induced tremor

It has recently been found that tremor in patients on long-term lithium therapy has a lower frequency than that of normal physiological tremor and is likely to have an extrapyramidal component (Tyrer et al, 1981). Other extrapyramidal signs and symptoms have been found with chronic lithium therapy (Shopsin and Gershon, 1975; Baastrup et al, 1976; Branchey et al, 1976; Asnis et al, 1979). These extrapyramidal effects differ from the pseudoparkinsonism produced by antipsychotic drugs in that they do not respond to antiparkinsonian drug treatment (Schou, 1970; Tyrer et al, 1980).