Introduction: Pantothenate kinase-associated neurodegeneration (PKAN) is a rare autosomal recessive disorder, characterized by progressive iron accumulation affecting especially the pallidum and SNr. Since 2001, DBS targeting GPi or alternatively STN or the motor thalamus has been attempted.
Methods: Our systematic review of the literature encompasses 100 cases of DBS for PKAN (58 classic, 14 atypical, 28 unknown).
Results: Despite being affected by iron accumulation, neuronal degeneration and gliosis, GPi was by far the most common target (88/100). Patients with classic PKAN underwent DBS implantation surgery at the median age of 11 years (range 6-34) after a median disease duration of 7 years. 10/58 classic PKAN cases underwent emergent DBS implantation during a dystonic storm. Atypical PKAN cases were operated at a median age of 31 years (range 17-46), after a median disease duration of 15 years.
The mean BFMDRS-M reduction after 1 year was 26% but was more prominent in atypical (45%) than in classic (16%) PKAN cases. The response rate (?30% dystonia improvement at 1 year) was 35% in classic and 73% in atypical PKAN. Preoperative dystonia severity, disease duration, proportion of life lived with symptoms, and fixed skeletal deformities and/or muscle contractures were not predictive of outcome.
GPi-DBS slightly improved functional disability (BFMDRS-D -13%), and may have improved pain, cognitive scores and quality of life at 1 year postoperatively.
After 4-7 years, this improvement was lost, although the relative contribution of disease progression and loss of DBS effect is unknown. The rate of infection and hardware complications was in line with other types of dystonia. However, 2/100 patients died within 3 months and the complication rate was particularly high in patients operated during a dystonic storm.
Conclusions: There is level III evidence that GPi-DBS can reduce dystonia and improve functionality in PKAN, especially in atypical cases.
Patient Care: This work extracts useful data from all published PKAN cases treated with DBS. It may help for patient counselling and decision making.
Learning Objectives: "By the conclusion of this session, participants should be able to: 1) Describe the importance of DBS for PKAN, 2) Discuss, in small groups, the information that can be given to patients considering this surgery, 3) Identify predicting parameters for success and complications in this type of surgery.