Altered Thalamic Connectivity Due to Focused Ultrasound Thalamotomy in Patients with Essential Tremor.

BACKGROUND: Although stereotactic ablation surgery is known to ameliorate involuntary movement dramatically, little is known regarding alterations in whole-brain networks due to disruption of the deep brain nucleus. To explore changes in the whole-brain network after thalamotomy, we analyzed structural and functional connectivity alterations using resting-state functional magnetic resonance imaging and diffusion tensor imaging in patients with essential tremor who had undergone focused ultrasound (FUS) thalamotomy. METHODS: Seven patients with intractable essential tremors and 7 age-matched healthy controls were enrolled in the study. The tremor score in essential tremor patients was assessed, and resting-state functional magnetic resonance imaging and diffusion tensor imaging were performed before and 3 months after left ventral intermediate nucleus thalamotomy using FUS. RESULTS: There was a significant improvement in the tremor of the right hand after FUS thalamotomy. Seed-based functional connectivity analysis revealed a significant increase in functional connectivity between the left thalamus and the caudal part of the dorsal premotor cortex after FUS thalamotomy. Structural connectivity analysis did not detect statistically significant changes between before and after FUS. There was no correlation between the changes in functional connectivity and tremor score. CONCLUSIONS: Although the number of cases is small, our results show that functional connectivity between the thalamus and the premotor cortex increases after the amelioration of tremors by FUS thalamotomy. The lack of correlation between increased functional connectivity and clinical tremor scores suggests that the observed increase in functional connectivity may be a compensatory change in the secondary sensorimotor changes that occur after thalamotomy.

[A case of Möbius syndrome with congenital facial palsy and supranuclear oculomotor palsy].

An 18-year-old man with congenital weakness in the facial and mastication muscles was referred to us. His facial senses were intact; however, the bilateral massetter and facial muscles were extremely weak and atrophic. He presented lagophthalmos and had difficulty in closing his mouth. The voluntary movements of his left eye, such as abduction, adduction, and elevation, were partially impaired, without the impairment of the Bell phenomenon. Nerve conduction studies of the facial nerves revealed normal distal latencies for bilateral orbicularis oculi. Blink reflexes were not evoked on both sides. Needle electromyography showed a chronic neurogenic change in the tongue. A biopsy of the biceps brachii and skin did not show abnormality. We diagnosed his condition as Möbius syndrome with congenital facial palsy and supranuclear oculomotor palsy. Möbius syndrome, which manifests itself as congenital and non-progressing facial and abducens palsy, is associated with many clinical symptoms and is probably heterogenous nosological entity. Although several cases of Möbius syndrome with supranuclear binocular elevation palsy were previously known, this is the first case of Möbius syndrome presenting supranuclear monocular elevation palsy.