Objective: To report a rare case of lentiform nucleus cavernoma with phasic-predominant hemidystonia and sustained BoNT response.

Background: Cerebral cavernomas rarely present with movement disorders. Secondary dystonia due to structural basal ganglia lesions is challenging to manage. Hemidystonia with prominent phasic dystonia due to cavernoma has been rarely reported.

Method: Case report. Video content showing the dystonia included.

Results: We report a 56-year-old woman with a prior history of right facial paresis who presented with a one-year progressive history of right-hand involuntary movements evolving to involve the right leg and foot. Birth, developmental, and family histories were unremarkable, with no prior neuroleptic exposure or psychiatric illness. Examination revealed right facial nerve paresis with superimposed hemifacial spasm, and right-sided hemidystonia characterized by shoulder abduction and hyperextension, wrist flexion with prominent phasic dystonia, near-continuous athetotic finger movements, and right foot inversion and plantarflexion with athetotic toe movements. MRI demonstrated a 2.4 × 3.1 × 2.0 cm cavernous malformation centered within the left lentiform nucleus, external capsule, and subinsular region, without mass effect or diffusion restriction. Botulinum toxin injections were administered with EMG guidance and achieved marked symptomatic improvement with sustained one-year treatment-free remission.

Conclusion: This rare case of cavernoma-induced phasic hemidystonia implicates the lentiform nucleus and its striatopallidal projections as the critical anatomical substrate, with disrupted efferent pathways generating aberrant thalamic input to the premotor cortex. Hemosiderin-induced neuroinflammation and gliosis are likely drivers of pathological basal ganglia oscillations, manifesting clinically as phasic rather than tonic dystonia. Notably, peripheral chemodenervation with botulinum toxin can produce a sustained and durable remission even in phasic dystonia, a finding with important therapeutic implications for cavernoma-induced hemidystonia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/phasic-hemidystonia-secondary-to-cavernoma-a-case-of-sustained-response-to-botulinum-toxin/