PubMed · 15085680
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Joseph H Friedman. 2004. DBS.. https://pubmed.ncbi.nlm.nih.gov/15085680/
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F waves were recorded from abductor hallucis muscle in eight Parkinsonian patients with deep brain stimulation (DBS) electrodes surgically implanted in their Vim thalamic nucleus in two conditions of DBS ON and OFF. Patients with relatively anteriorly located electrodes exhibited a significant reduction in F wave duration and also in the UPDRS rigidity score of the corresponding foot when the DBS was ON. In contrast, patients with relatively posteriorly located electrodes exhibited no significant difference in F wave duration in the two DBS ON and OFF conditions. The rigidity UPDRS score in the corresponding foot diminished very little in the latter group. Both groups had great improvement in their tremor at rest UPDRS score in that foot when the DBS was ON. Vim surgery is generally accepted to affect tremor mechanisms. However, surgical intervention in anterior parts of Vim has been reported to affect rigidity mechanisms. This correspondence of these two symptoms of rigidity and tremor with the two locations of anterior and relatively posterior Vim may indicate the contribution of mechanisms of rigidity, but not tremor, in enhancement of F wave duration and hyper excitability of spinal motoneuron.
Essential tremor can be surgically treated by thalamotomy or deep brain stimulation. During the surgical procedure for both of these procedures, a transient microthalamotomy effect has been observed. This benefit is usually short-lived and appears to be predictive of patient outcome. This report describes a patient who underwent a temporary placement of a stimulating electrode within the ventral intermediate nucleus of the motor thalamus. The procedure was aborted intraoperatively and the patient demonstrated a microthalamotomy effect. This microthalamotomy effect has remained persistent for 24 months, and the patient remains tremor free. This case report lends evidence to the idea that the volume of motor thalamus responsible for tremor may be small and precise. By recognizing the benefit obtained from small lesions with minimal tissue manipulation, surgeons can continue to refine the target for movement disorder surgery.
In a case of Parkinson's disease, the patient was treated with deep brain stimulation of the subthalamic nucleus (STN-DBS). STN-DBS affected the mental competence of the patient and ethical questions were raised about the decision as to the direction of further treatment. The patient was asked for his opinion on the therapeutic options during a phase of non-stimulation and chose to be stimulated and admitted to a psychiatric hospital because of mental incompetence rather than remaining unstimulated, mentally competent but bedridden. Developments in the neurosciences (including STN-DBS) raise a number of different fundamental (theoretical and philosophical) as well as practical questions. STN-DBS can have various unintended (behavioural) effects. In the case presented, more weight was rightly given to the mental competence of the unstimulated patient, although comments can be made with regard to his decision making, as his choice was made in a phase of serious distress. Attention is paid to the relevance of a so-called self-binding directive. STN-DBS is not morally neutral and the case involves a tragic dilemma: a conflict between irreconcilable duties for the physician. The further development and proliferation of STN-DBS requires caution and moral deliberation. It remains important to search for alternative treatment strategies with less undesirable side effects.