Effects of chronic lithium treatment on the peripheral nervous system.
BACKGROUND
Although lithium carbonate is widely used in the treatment of mood disorders, symptoms suggesting toxic effects on the peripheral nervous system may emerge even in subjects whose serum lithium levels remain within the recommended therapeutic range.


METHODS
Electroneuronographic (ENG) parameters (motor nerve conduction velocity of peroneal and median nerves, sensory nerve conduction velocity of sural and median nerves, amplitude of motor potential of peroneal and median nerves, and amplitude of sensory action potential of the median nerve at the wrist and the sural nerve) were investigated in 2 groups (N = 34) of patients suffering from bipolar affective disorder (DSM-III-R, DSM-IV) undergoing maintenance treatment with lithium carbonate for at least 1 year (mean = 2.06 years) in monotherapy. For 12 patients, ENG results were compared with pretreatment values, whereas in the other 22 cases, only data relevant to posttreatment were available. Fifty-four healthy subjects and 20 patients with recurrent major affective disorder (unipolar and bipolar) never treated with lithium made up the comparison groups.


RESULTS
Compared with the 2 comparison groups, patients on chronic lithium treatment showed significant reduction of motor nerve conduction velocity of peroneal and median nerves, sensory nerve conduction velocity of sural and median nerves, amplitude of motor potential of peroneal and median nerves, and amplitude of sensory action potential of the median nerve at the wrist and the sural nerve. The comparison with the assessment made prior to lithium treatment also showed significant changes; after a period of treatment with lithium varying from 2 to 8 years (mean = 5.2 years), significant reductions were found on motor and sensory nerve conduction velocity and on amplitude motor potentials and sensory action potentials.


CONCLUSIONS
Chronic maintenance treatment with lithium affects the peripheral nerves, even if the impairment rarely is such as to warrant discontinuation of treatment. Monitoring of ENG results could be useful for the early detection of neurotoxicity of lithium.
Faravelli
C
C
Department of Neurological and Psychiatric Sciences, University of Florence, Italy.
Di Bernardo
M
M
Ricca
V
V
Benvenuti
P
P
Bartelli
M
M
Ronchi
O
O
D000200:Action Potentials / Q000187:drug effects; D000328:Adult; D001714:Bipolar Disorder / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control; D003866:Depressive Disorder / Q000188:drug therapy / Q000503:physiopathology / Q000517:prevention & control*; D004576:Electromyography; D005260:Female; D006801:Humans; D016651:Lithium Carbonate / Q000009:adverse effects* / Q000494:pharmacology / Q000627:therapeutic use; D008297:Male; D008475:Median Nerve / Q000187:drug effects / Q000503:physiopathology; D008875:Middle Aged; D009431:Neural Conduction / Q000187:drug effects; D017933:Peripheral Nervous System / Q000187:drug effects* / Q000503:physiopathology; D010523:Peripheral Nervous System Diseases / Q000139:chemically induced* / Q000175:diagnosis / Q000503:physiopathology; D010543:Peroneal Nerve / Q000187:drug effects / Q000503:physiopathology; D013497:Sural Nerve / Q000187:drug effects / Q000503:physiopathology
D016651:Lithium Carbonate