Membrane Mechanisms of Tremor

A number of neurological and psychogenic disorders present with tremor. In some, there is a known structural abnormality, while in others the pathophysiology is unknown. For example, the scarcity of a neurotransmitter from presynaptic neuronal degeneration causes tremor in degenerative cerebellar or basal ganglia disorders (Jankovic and Tolosa 2007 ) . Instability of the brainstem neural integrators may cause tremor of the eyes (pendular nystagmus) in patients with demyelinating disorders (Das et al. 2000 ) . However, the anatomical and pathophysiological correlates of some tremor disorders, for example essential tremor, are unsettled. Regardless of the primary etiology (structural de fi cit or idiopathic) contemporary literature suggests that oscillations can arise at the level of neuronal membranes. More recently, it was proposed that membrane hyperexcitability could cause essential tremor (Shaikh et al. 2008 ) . In support of this hypothesis, commonly used drugs (e.g., primidone, propranolol, gabapentin, topiramate) also have membrane stabilization effects (O’Suilleabhain and Dewey 2002 ; Zesiewicz et al. 2005 ) .