Objective: To describe our series of patients with refractory tremor eventually treated with perampanel and to analyse its clinical outcomes.

Background: Up to 40% of patients with essential (ET) or dystonic (DT) tremor are refractory. An increase in excitatory neurotransmitters has been hypothesized. Perampanel, an antiepileptic drug with AMPA receptor antagonist effect, may thus be potentially useful [1]

Method: Retrospective analysis of the electronic records of patients with refractory ET or DT of our movement disorders unit along a 2-year period.

Results: Eleven patients (7 women, mean age 72 ± 8 years) who were prescribed perampanel due to insufficient tremor control were analysed. Four were diagnosed with ET and 7 with DT, most of them with cephalic, vocal and upper limbs involvement, and mean previous follow-up of 7,6 ± 4,0 years. Previous/concomitant treatments included propranolol (mean dose 70 mg, range 20-120), primidone (250 mg, 125-375), clonazepam (1 mg, 0,5-2) and cervical botulinum toxin injections (4 cases). Mean perampanel dose was 4 mg (2-8 mg) qid, with a slow titration along several weeks (from 2 mg each 48 hours to effective dose, intolerance or 8 mg qid), and follow-up 2,4 ± 1,3 months. Four patients improved, 2 were diagnosed with DT (Clinical Global Impression-Improvement, CGI-I, scale score of 1) and 2 with ET (CGI-I score 2). Five patients (3 in monotherapy) reported mild-moderate adverse events (dizziness, sleep disturbances) at a mean dose of 3,2 mg (range 2-4 mg), and one patient was admitted due to ataxia and confusion at 8 mg qid, overall leading to discontinuation in 5 [table 1].

Conclusion: Perampanel may be effective in some patients with refractory tremor, albeit blinded randomized controlled trials are warranted to confirm this hypothesis. Poor tolerability may hinder dose escalation in a subset of patients.

References: 1.- Gironell A, Pascual-Sedano B, Marín-Lahoz J. Perampanel, a new hope for Essential tremor: An open-label trial. Parkinsonism Relat Disord. 2019 mar;60:171-172.

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