Background: Dystonia is a complex clinical syndrome originated by a wide range of aetiologies. The diagnosis of dystonia is made after the evaluation of aetiological, phenomenological and genetic factors.1 Medications, except in patients with dopa-responsive dystonia, are of limited efficacy. Botulinum toxin injections are not applicable to patients with generalised dystonia, since many muscular groups contribute to disability.2 Clinical studies in children and adults with primary generalised dystonia (PGD) have reported beneficial effects of bilateral GPi deep brain stimulation (DBS) in both motor symptoms and disability produced by dystonia3 4 5 as well as a favourable impact of DBS in the health-related quality of life (HRQoL).6 Some clinical aspects of GPi stimulation in primary dystonia still remain controversial such as the influence of disease duration or age at onset in determining the postoperative clinical outcome. Results: The authors report the results of a multicentric study designed to assess the tolerability and clinical effects of bilateral pallidal DBS on motor impairment, functional disability, quality of life, pain and mood in patients with medically refractory primary generalised or segmental dystonia.

Purpose: Although large amplitude evoked potentials (EPs) are typically associated with progressive myoclonic epilepsy patients, giant EPs imply central nervous system (CNS) hyperexcitability and can be seen in various nonepileptic disorders. Methods: We performed a retrospective chart review including history, physical examination, imaging and diagnostic studies of nonepileptic patients with large amplitude somatosensory evoked potentials (SSEPs) and visual evoked potentials (VEPs) during 2007 to 2013. Large amplitude EPs were defined as follows: VEPs (N75-P100) >18 μV; and SSEPs (N20-P25) >6.4 μV. Recording montage for VEPs was Oz-Cz and SSEPs C3′/C4′-Fz. Results: Fifty-two patients (33 females, 19 males; age range, 9–90 years) were identified. No CNS pathology was detected in 7 patients. All remaining patients were diagnosed with new CNS disorders including: vascular (37%); myelopathies (13%); demyelinating (11%); space occupying lesions (8.7%); syringomyelia (8.7%); hydrocephalus (6.5%); Vitamin B-12 deficiency (4.3%); multiple system atrophy (4.3%); and toxins (2.2%). Conclusions: This study supports the notion that large amplitude EP implies CNS hyperexcitability and CNS disease. These results confirm the utility of EP studies in patients with suspected CNS pathology.