Objective:

To present two cases of intraparenchymal cysts, a rare complication of deep brain stimulation (DBS) in patients with movement disorders. 

Background:

Formation of an intraparenchymal cyst following DBS electrode placement is a very rare complication. Only a few case reports exist and as a result, there is paucity of knowledge on its etiology, pathogenesis, prevention and treatment.  

Design/Methods:

A chart review was done on two cases that had intraparenchymal cyst formation following DBS electrode placement at our medical center. In addition, we reviewed the literature to compare with our cases.  

Results:

Patient A is a 79 y.o. male who underwent a left VIM thalamic lead placement and Patient B is a 64 y.o. underwent bilateral VIM lead placement for essential tremor. Both patients had a period of improvement in tremor before starting to experience new neurological deficits about 10 months and 2 months after lead placement, respectively. Patient A experienced right foot weakness, right arm weakness, and subjective decline in cognition while Patient B experienced an acute episode of altered mental status in the emergency department while under cardiac monitoring. Upon imaging, a cyst was found at the tip of the DBS lead in Patient A’s left thalamus and Patient B’s right thalamus. Infectious workup was negative indicating the cysts to be non-infectious. The brain electrodes were removed in both patients with resolution of neurological deficits and cyst regression on repeat imaging. Patient A continued to have tremor suppression for a year despite electrode removal while Patient B had an immediate tremor return to the pre-DBS baseline.  

Conclusions:

Electrode explanation resulted in cyst regression with resolution of right hemi-body weakness in Patient A and altered mental status in Patient B. There is a need for reporting this very rare complication of DBS surgery to better understand its etiology, pathogenesis, treatment and prognosis.