Faculty Bibliography

Data regarding the clinical experience of movement disorders subspecialty training are currently not available. In order to provide information to help design a well-rounded clinical experience, we reviewed the number and types of patients seen by all clinical movement disorders fellows over the course of 1 year at Columbia University Medical Center (CUMC). We conducted a retrospective analysis of all patients seen by four full-time clinical fellows and one part-time fellow during the 2001-2002 academic year, using billing records to tabulate all clinic visits and patient charts to certify diagnosis. One thousand six hundred sixty-two patients (1,132 new and 530 follow-ups) were seen by five fellows. Each full-time fellow evaluated and treated a mean of 263 new patients, 116 follow-up patients, and 15 in-patient consultations. The part-time clinical fellow evaluated and treated 81 new patients and 65 follow-up patients. Approximately half of the new patients had idiopathic Parkinson's disease. Full-time fellows saw equivalent numbers of patients but they evaluated few patients with uncommon movement disorders. Weekly video rounds allowed all fellows to see many more patients, aiding the recognition of movement phenomenology and enhancing understanding of diagnoses and treatment strategies. Thus, CUMC fellows evaluate a large number of patients with a wide range of diagnoses within a 1-year period. Video rounds allow greater exposure to uncommon diagnoses. Similar data from other movement disorder training programs are needed to help create guidelines for formal accreditation and to improve clinical training in this subspecialty.

It is difficult to predict precisely the final neurologic outcome from cardiac arrest and accompanying cerebral hypoxia. Although rare, several movement disorders may arise as a consequence of hypoxic injury, including myoclonus, dystonia, akinetic-rigid syndromes, tremor, and chorea. Dys-function of various portions of the central nervous system, including the basal ganglia, thalamus, midbrain, and cerebellum, is implicated in the pathogenesis of these posthypoxic movement disorders. The development of animal models of posthypoxic movement disorders and of newer imaging techniques applied to human patients who have movement disorders after hypoxic episodes has improved understanding of the pathophysiology of posthypoxic movement disorders and has suggested newer treatments. Many outstanding questions remain, however. What factors promote susceptibility to the development of posthypoxic movement disorders? Why do patients who have similar clinical hypoxic insults develop markedly dis-similar movement disorders? Why are the basal ganglia especially vulnerable to cerebral hypoxia? Why do some movement disorders occur in delayed fashion and progress for years after the hypoxic insult? Is the pathogenesis of progressive posthypoxic movement disorders related to that of neurodegenerative diseases? What are the most effective medications for the various posthypoxic movement disorders? Is there a role for deep brain stimulation in the treatment of posthypoxic movement disorders? We anticipate that current and future research in the area of posthypoxic movement disorders will reveal answers to some of these important questions.

The authors performed an open-label, rater-blinded, add-on study of sodium oxybate in 20 patients with ethanol-responsive myoclonus or essential tremor. Blinded ratings of videotaped examinations showed improvements in myoclonus at rest, stimulus-sensitive myoclonus, action myoclonus, functional performance, and postural and kinetic tremor. Tolerability was acceptable, and more than half of the patients chose to continue treatment after the trial. Double-blind placebo-controlled studies in these disorders are warranted.

OBJECT: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) performed using intraoperative microelectrode recording (MER) to adjust electrode placement has become a widely used treatment for patients with advanced Parkinson disease (PD). Few studies have been conducted to examine the location of implanted electrodes relative to the intended target, and even fewer have been undertaken to investigate the degree to which variations in the location of these electrodes impacts their clinical efficacy. This study was performed to examine these issues. METHODS: The authors located 52 bilaterally implanted DBS electrode tips on postoperative magnetic resonance (MR) images obtained in 26 consecutive patients. Postoperative and preoperative planning MR images were merged to determine the DBS electrode tip coordinates relative to the midcommissural point. Surgical records listed the intended target coordinates for each DBS electrode tip. Clinical outcome assessment included the Unified PD Rating Scale (UPDRS) motor score at 1 year, standardized questionnaires, and routine follow-up visits. The mean difference between electrode tip location and intended target for all 52 electrodes was less than 2 mm in all axes. Only one electrode was farther than 3 mm from the intended target, and this was the only electrode that had to be replaced due to lack of clinical efficacy (lack of tremor suppression); its reimplantation 4 mm more medially provided excellent tremor control. High correlation coefficients indicate that the MR imaging analysis accurately determined the anatomical location of the electrode tips. Blinded videotape reviews of UPDRS motor scores comparing effects of stimulation in patients who were 'on' and 'off' medication identified subgroups in whom there was minimal and maximal stimulation response. Patients in these subgroups had no differences between the MR imaging-determined actual electrode tip location and its intended location. Similarly, improvements of dyskinesias and severity of symptoms encountered during the wearing-off period for the drug did not correlate with variations of electrode tip location. CONCLUSIONS: The findings in this study lead the authors to suggest that a DBS electrode placed anywhere within a 6-mm-diameter cylinder centered at the presumed middle of the STN (based on stereotactic atlas coordinates) provides similar clinical efficacy. Future studies may be warranted to evaluate prospectively the degree to which MER modification of the anatomically and/or image-determined target improves clinical efficacy of DBS electrodes