Asterixis and toxic encephalopathy induced by gabapentin.
OBJECTIVE
To date, only one case of asterixis associated with the use of gabapentin (GBT) has been reported. No data, instead, are available on the occurrence of asterixis related to a dementing encephalopathy during GBT therapy in the elderly.


METHODS
Case reports of two elderly patients, one with asterixis, the other with asterixis and encephalopathy, associated with the use of GBT, as adjunctive therapy, at dosages of 900 to 3600 mg/day are given. In one patient, GBT was added to oxcarbazepine (OXCBZ).


RESULTS
Both patients experienced resolution of the clinically apparent asterixis, and of the toxic encephalopathy, on discontinuation or reduction of GBT dosages. One patient developed asterixis after drug rechallenge. In the patient on OXCBZ, the analysis of the electromyogram (EMG) activity showed the occurrence of a subclinical asterixis.


CONCLUSIONS
Our study indicates that high doses of GBT may induce asterixis related to a reversible encephalopathy. Low doses of GBT, instead, may induce a disabling asterixis when given in combination with OXCBZ because of a synergistic interaction between these drugs.
Sechi
GianPietro
G
Neurological Clinic, University of Sassari, Viale San Pietro, 10, 07100 Sassari, Italy. gpsechi@ssmain.uniss.it
Murgia
Bastianino
B
Sau
GianFranco
G
Peddone
Luigi
L
Tirotto
Antonella
A
Barrocu
Marianna
M
Rosati
Giulio
G
D000085:Acetates / Q000009:adverse effects* / Q000627:therapeutic use; D000368:Aged; D000588:Amines; D000927:Anticonvulsants / Q000009:adverse effects* / Q000627:therapeutic use; D001921:Brain / Q000473:pathology; D001927:Brain Diseases / Q000139:chemically induced* / Q000473:pathology / Q000503:physiopathology*; D002220:Carbamazepine / Q000031:analogs & derivatives* / Q000627:therapeutic use; D003509:Cyclohexanecarboxylic Acids; D004409:Dyskinesia, Drug-Induced / Q000503:physiopathology*; D004576:Electromyography; D020329:Essential Tremor / Q000150:complications / Q000188:drug therapy; D005260:Female; D000077206:Gabapentin; D006801:Humans; D008279:Magnetic Resonance Imaging; D009044:Motor Cortex / Q000503:physiopathology; D000078330:Oxcarbazepine; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D000927:Anticonvulsants; D003509:Cyclohexanecarboxylic Acids; D002220:Carbamazepine; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D000078330:Oxcarbazepine