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Advances in primary writing tremor

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Abstract

Primary writing tremor (PWT) is considered to be a type of task-specific tremor in which tremor predominantly occurs and interferes with handwriting. The pathophysiology of PWT is not clear. Primary writing tremor may be a variant of essential tremor, a type of focal dystonia such as writer’s cramp, or a separate nosological entity. Botulinum toxin injections and deep brain stimulation may be treatment choices for primary writing tremor.

Introduction

Tremor is an involuntary oscillation of a body part and is the most common form of movement disorder. Task-specific tremor is largely or solely limited to a specific task or movement, such as writing, speaking, smiling, or standing [1]. Primary writing tremor (PWT) is considered to be a type of task-specific tremor in which tremor occurs and interferes with handwriting [2], [3], [4], [5]. The pathophysiology of PWT is unknown [3], [6], [7]. There is still some controversy as to whether PWT is a variant of essential tremor [7], [8], a type of focal dystonia such as writer’s cramp [9], or a separate nosological entity [2], [6].

Section snippets

Clinical manifestation of PWT

First described in 1979 by Rothwell et al. [10], the term PWT is used to define a specific action tremor in which pronation of the forearm elicits a pronation/supination tremor during writing but not seen during other arm movements. They described a right-handed young man who presented with difficulty writing caused by bursts of tremor which occurred whenever the right forearm was pronated. Patients are classified as having either type A or type B PWT depending on whether tremor appears during

Hypothesis

The origin of the entity remains unknown, but that the following findings argue for or against PWT being an essential tremor variant, a type of dystonia, or a separate entity.

Treatment of PWT

No double-blind studies of the condition have been reported. Medical treatment includes the use of propranolol, primidone, and anticholinergic medications [4]. Treatment of PWT with for oral drugs may not be effective and functional neurosurgery has been advocated for medication-resistant patients [24]. Treatment of essential tremor with propranolol, primidone, diazepam, topiramate may only be successful in about 50% of cases [25] (Table 2).

Sixty percent of patients treated reported that they

Summary

Primary writing tremor is a condition in which tremor predominantly or only occurs during writing. Patients are classified as having either type A or type B PWT depending on whether tremor appears during writing (type A: task induced tremor) or while writing or also when adopting the hand position normally used for writing (type B: positionally sensitive tremor). The pathophysiology of PWT is different from that of writer’s cramp and partially also from that of essential tremor. PWT may be a

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    The review of this paper was entirely handled by a Co-Editor-in-Chief, Zbigniew Wszolek.

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