We read with interest the abstract by Olson et al. (I). They showed that gabapentin improves rigidity, bradykinesia, and tremor in parkinsonism and Parkinson's disease (PD).
We administered gabapentin, 900 mg per day, in an open trial to seven nondemented patients with PD who had painful dystonia, dyskinesia, and motor fluctuations (Table 1) Gabapentin effect was measured with the Unified PD Rating Scale (UPDRS) and Obeso Dyskinesia Rating scale (2).
Gabapentin improved interdose symptoms (painful dystonia, biphasic dyskinesias) and motor fluctuations (on time). Palpitations, perspiration, and mood changes also seemed to improve, although this was not quantitatively evaluated. We also observed the beneficial effects on parkinsonian symptoms proposed by Olson et al. (Table 2).
The mechanism by which gabapentin exerts its antiparkinsonian effects is unknown. It does not exhibit affinity to dopamine D, or D,, or glutamatergic or cholinergic receptors (3,4).
Gabapentin was tolerated well. Only two patients developed somnolence, which could be managed with dose reductions.