Remarkable improvement of primary orthostatic tremor using perampanel

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(2020) 2:3

Neurological Research and Practice

LETTER TO THE EDITOR

Open Access

Remarkable improvement of primary orthostatic tremor using perampanel Marcus Grobe-Einsler1,2

and Oliver Kaut1*

Abstract Management of primary orthostatic tremor (POT) remains challenging, and medication is often ineffective. We report the case of a 53-year-old female with orthostatic tremor for 6 years who was refractory to gabapentin, clonazepam, primidone and propranolol. After treatment with 4 mg/day perampanel, she reported almost complete resolution of tremor. The diagnosis of POT was confirmed by tremor analysis using surface electromyography. Our report shows the potential use of the novel AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor antagonist perampanel for the treatment of POT. To date, only two similar patients, one refractory to treatment and the other previously treated with clonazepam only, have been reported. We would like to note that our patient was refractory to all previous therapy and responded to a low dose of perampanel without side effects. The striking clinical improvement suggests a putative role of glutamate in the pathophysiology of orthostatic tremor. Keywords: Orthostatic tremor, Tremor, Perampanel

Introduction Primary orthostatic tremor is a rare neurologic movement disorder characterized by unsteadiness in gait and (more pronouncedly) in stance due to a pathognomonic 13–18 Hz tremor that can be detected by surface EMG of both legs while standing. Involvement of the upper extremities is less frequent but has also been described. The pathophysiology of POT remains poorly understood, and limited treatment options are available. To date, multiple therapeutic approaches, of which gabapentin, benzodiazepines, primidone, propanolol, pregabalin and phenobarbital have been shown to be likely or possibly beneficial, have been tried [8]. The clinical response is frequently low, and the non-responder rate remains high [2]. We herein report a 53-year-old female with a clinical and electrophysiological diagnosis of medication-resistant orthostatic tremor who experienced significant improvement under therapy with perampanel.

* Correspondence: [email protected] 1 Department of Neurology, University Clinic Bonn, Venusberg-Campus 1, 53105 Bonn, Germany Full list of author information is available at the end of the article

Case The first symptoms occurred 6 years before diagnosis; they occurred at high frequency and included low amplitude tremor seconds after standing up that was less pronounced while walking and suspended during rest. POT was diagnosed based on surface EMG. Upper extremity functions were not impaired at the time of diagnosis. The only comorbidity was recurrent depressive episodes beginning 5 years before the onset of tremor. Treatment with gabapentin (2400 mg/day), clonazepam (4 mg/day), primidone (500 mg/day) and propanolol (unknown dose) showed an insufficient clinical response with disease progression. In parallel, depressive episodes worsened as the tremor progressed