Chronic deep brain stimulation for movement disorders

Deep brain stimulation of CM/PF of thalamus could be the new elective target for tremor in advanced Parkinson's Disease?

Aim of this study was to investigate whether Deep Brain Stimulation (DBS) of the Centre Median Nucleus/Parafascicular (CM/PF) Complex is useful in reducing extrapyramidal symptoms in advanced Parkinson's Disease (PD) patients. In particular, we compared the action of CM/PF and subthalamic nucleus (STN) DBS on resting hand tremor using EMG surface of ulnar and radial right-hand muscles. Our results show that C/M DBS is very effective in reducing tremor, indicating this complex as a new target in advanced PD patients.

Efficacy of bilateral subthalamic nucleus (STN) stimulation in Parkinson's disease

BACKGROUND

Deep brain stimulation (DBS) has, for the most part, replaced irreversible stereotactic coagulations in the surgical treatment of advanced Parkinson's disease. This study was undertaken to evaluate the benefits of bilateral STN stimulation related to its potential risks and side effects.

METHOD

Twenty-nine consecutive Parkinsonian patients treated with STN-DBS were prospectively followed-up. Effects on Parkinsonian symptoms were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS). The evaluation was performed preoperatively and included postoperative follow-up evaluations at one and twelve months. All evaluations were made during the patient's best on-medication phase and postoperative follow-ups were conducted under both stimulator-on and stimulator-off conditions by a blinded neurologist. A neuropsychologist also evaluated the patients at every visit.

FINDINGS

Two patients were excluded from the analysis because of severe surgical complications and three for an infection demanding the removal of the stimulator material. Other complications and side effects were clearly milder and temporary. At twelve months after surgery dyskinesia scores in the UPDRS were 53% lower than preoperative values. The results of the UPDRS motor scores improved 31.4% and activities of daily living (ADL) scores increased 19% compared with the preoperative situation. Also, the daily levodopa dose was 22% lower. Neuropsychological changes were minor, except for some deterioration in verbal fluency.

CONCLUSION

The majority of Parkinsonian patients experienced significant and long lasting relief from their motor symptoms and an improvement in ADL functions due to DBS-STN therapy when evaluated at the best on-medication phase.

[Clinical applications of stereotaxic methology]

Cerebral stereotaxy is an old methodology allowing an accurate approach of a lesion or a function, in constant renewal with the introduction of computers and robotic. There is a natural complementarity with recent neuroradiological investigations and together, it is possible to reach cerebral deep-seated or functional structures with inocuity and fiability for diagnosis and/or therapy. Its application is very large and also influences neuronavigation procedures, current in conventional neurosurgery. Tumoral stereotaxy is commonly used and achieves a better adaptation of the therapeutical strategy according to the lesions' site and histological diagnosis. The development of functional stereotaxy is associated with the interest of the neurosurgical treatment of involuntary abnormal movements, without forgetting different aspects of surgery of chronic pain and intractable epilepsies. Moreover, the stereotactic methodology leads the concept of radiosurgery, which is in some indications a true alternative to open surgery (arteriovenous malformations, vestibular schwannoma, metastasis) under the control of accurate selection in a multidisciplinary approach.

Effect of bilateral stimulation of the subthalamic nucleus on parkinsonian voice

The purpose of this study was to assess several acoustic features of the voices of 26 parkinsonian patients under two conditions, with and without bilateral chronic stimulation of the subthalamic nucleus (STN) to estimate the effectiveness of this procedure on parkinsonian speech. When compared to unstimulated patients, stimulated patients showed longer duration of sustained vowels, shorter duration of sentences, nonsense words, and pauses, more variable fundamental frequency (f0) in sentences, and more stable f0 during sustained vowels. Relative intensity was unchanged in both conditions. Further acoustic analyses are warranted to clarify the role of STN stimulation on parkinsonian speech.