Lithium Neurotoxicity

Timothy C. Hain, MD  • Page last modified: May 28, 2021

Overview

Lithium is a standard treatment for acute mania and is also used as a preventative agent for recurrent bipolar and unipolar affective disorders (i.e. conditions that can include severe depression). The therapeutic range for this medication is rather narrow and acute reversible neurotoxicity is frequently encountered with lithium overdose, and rarely encountered with normal levels as well. Tremor is a common side effect considered tolerable. From reports in the literature, lithium neurotoxicity is mainly recognized by a combination of dizziness and downbeating nystagmus. Occasional individuals have permanent neurological damage after the lithium is stopped.

In the single autopsy study, damage was found in the MVN and NPH (Corbett, Jacobson et al. 1989).  These are brainstem nuclei involved with vestibular function and gaze holding.

Case Example:

A 37 year old man with bipolar disorder, seen by the author of this page in 1994, developed ataxia after a lithium overdose 2 years prior to examination. On examination he had scanning speech, poor pursuit, and overshoot dysmetria. While it was not entirely clear that his symptoms are attributable to lithium overdose, he did show striking similarities to the cases reported by Apte and Langston above.

Summary:

Patients with downbeating nystagmus and on lithium should consider a trial of stopping lithium. Toxicity can occur with normal levels. This situation is a "judgement call" and depends on how critical lithium is to the person's well being as well as the relative likelihood that lithium is causing serious symptoms.


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