Objective: To report a patient with PKAN whose dystonia improved with bilateral pallidal (GPi) DBS.

Background: The benefits of GPi DBS are well-recognized in primary dystonia and tardive dystonia. However, responses in other secondary dystonias are variable. There have been a small number of reports of DBS outcome in PKAN.

Method: Case report.

Results: A previously healthy Thai man developed dystonia at age 18 years, initially in his legs, which then spread to his trunk and orofacial muscles, within a year. He also had remarkable speech and swallowing difficulties. His parents did not notice significant cognitive changes. There was no family history. While not aware of consanguinity, his parents came from the same province. Exam at age 20 revealed severe generalized dystonia with predominant lower cranial involvement (jaw opening), retrocollis and truncal extension (Burke-Fahn-Marsden Dystonia Rating Scale, BFMDRS, 87). Brain MRI revealed a classic “eye-of-the-tiger” appearance with iron accumulation in bilateral globus pallidi. Sanger sequencing disclosed homozygous c.856C>T (p.Arg286Cys) mutation in the PANK2 gene. With pharmacotherapies, there remained severe dystonia and impaired daily activities. He underwent bilateral GPi DBS at age 20, had been followed at 1 month for the initial programming and monthly for adjustments, which led to improvement in dystonia. Unfortunately, at 6-month follow-up, he had dystonic storm (BFMDRS 79.5) with tachycardia and CK of 910 U/L. This was triggered by severe dehydration from diarrhea 2 weeks prior. He was admitted and given intravenous hydration. The DBS setting was adjusted to Case+1-/1.3/90/100 (contact/amplitude [V]/pulse width [µsec]/frequency [Hz]) and Case+5-/2.0/90/100 in the right and left channels. He rapidly improved within 1-2 days, almost back to the pre-admission baseline. Upon 1-month follow-up with the same DBS setting, dystonia continued to slightly improve (BFMDRS 23). Pre- and postoperative videos will be presented.

Conclusion: This patient demonstrates benefits of bilateral GPi DBS for dystonia in PKAN which may be considered as an option in selected patients such as ones with severe disabling dystonia. Definite DBS outcome in our patient still requires long-term follow-up. Further larger studies with blinding will elucidate outcome, appropriate patient selection and DBS parameters in PKAN and other secondary dystonias.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/deep-brain-stimulation-dbs-in-pantothenate-kinase-associated-neurodegeneration-pkan-an-experience-in-a-thai-patient/