Objective: To describe the outcome of Deep Brain Stimulation (DBS) in patients with dystonia and prominent cerebellar atrophy.

Background: There is increasing evidence supporting the role of the cerebellum and cerebello-thalamo-cortical pathways in dystonia. Structural lesions in the cerebellum have been associated with cervical dystonia. Dystonia is often associated with cerebellar atrophy in several types of heredo-degenerative disease (SCA; ataxia telangiectasia, AOA1, AOA2, Niemann Pick type C, GM2 gangliosidosis, POLG) Abnormal cerebellar activation has been shown in PET and fMRI studies in focal dystonia. Transcranial magnetic stimulation showed abnormal cerebellar brain inhibition in dystonia. Viral tracer studies in non-human primates demonstrated reciprocal innervation between basal ganglia and cerebellum and many cortical areas in previous studies.

Methods: We performed a retrospective review in our database of all patients treated with DBS associating dystonia with severe cerebellar atrophy. We analyzed their clinical phenotype, etiology, cerebral MRI and other ancillary tests (DAT SPECT, PETscan and functional MRI (fMRI) when available) and DBS targets. Motor outcome was evaluated by BFMDRS.

Results: We identified 3 patients with marked cerebellar atrophy (2 adults/ 1 child; 2 M). There was a positive family history of cerebellar atrophy in two patients. Clinical examination showed truncal ataxia and generalized dystonia with predominant cranio-cervical and upper limb dystonia in both adults; the child showed generalized dystonia with predominant lower limb involvement. Exome sequencing of a panel of ataxia genes was negative for one patient; this study is ongoing for the other 2 patients. SCA 1, 2, 3, 6, 7, 17; AOA1; Friedreich ataxia; vitamin E, albumin; alpha-fetoprotein, Hexosaminidase A were negative or normal for all patients. EMG was normal. DAT SPECT showed low striatal binding in two patients. All patients were initially treated with globus pallidus internus (GPi) DBS for dystonia. GPi DBS improved dyskinesia in two patients. One patient was implanted in Vim/Vop thalamic nuclei replacing GPi leads due to inefficacy of GPi DBS with a milder improvement in dystonia.

Conclusions: GPi DBS was effective for dyskinesia in dystonia associated with cerebellar atrophy. Further research is needed to establish the role of cerebello-thalamo-cortical and cortico-striatopallido-thalamic pathways in this clinical syndrome.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/deep-brain-stimulation-in-three-patients-with-dystonia-and-severe-cerebellar-atrophy/