Internal globus pallidotomy in dystonia secondary to Huntington's disease

The prototypic motor feature of Huntington's disease (HD) is chorea, but parkinsonism and involuntary movements such as dystonia and myoclonus can also be present. Pallidotomy has been shown to be an effective treatment for medically refractory Parkinson's disease (PD). We performed bilateral microelectrode guided-stereotactic pallidotomies targeted at globus pallidum internus (GPi) to treat a 13-year-old patient diagnosed with Westphal variant of HD with intractable generalized dystonia and parkinsonism.

Intraoperative microelectrode recordings of GPi cells showed a relatively low firing rate, 29 +/- 14 Hz, with most neurons showing pauses. Acutely, after surgery, limb dystonia mildly improved but trunk dystonia persisted. Postoperative follow up 3 months later showed minimal clinical improvement in dystonic features with marked worsening of spasticity.

In our case, bilateral pallidotomy produced modest palliative functional improvement in dystonic features. Cellular firing patterns were markedly different than in PD and were similar to those found in dystonia.