Tremor in chronic inflammatory demyelinating polyneuropathy: Proof of unifying network model for dystonia

Traditional hypotheses for the pathogenesis of dystonia, the third most common movement disorder, have focused primarily on the basal ganglia. Contemporary theories have emphasized the role of the cerebellum. The modulation of peripheral proprioception also affects dystonia. We proposed a unifying network model for dystonia where the cerebellum, basal ganglia, and peripheral proprioception are connected in a circuit that forms the neural integrator network, ensuring steady position. We suggested that impairment anywhere along this circuit leads to common phenomenology-slow drifts followed by corrective movements, resembling dystonic tremor. We tested this concept in a patient with chronic inflammatory demyelinating polyneuropathy with resulting abnormal proprioception. Quantitative assessment of tremor in this patient revealed drifts in limb position followed by corrective movements and superimposed sinusoidal oscillations-consistent with neural integrator dysfunction. This unique case of chronic inflammatory demyelinating polyneuropathy describes the role of proprioception on the unifying network model for dystonia.