Treatment of a symptomatic fifth ventricle with spinal cord stimulation

Introduction: A cystic dilation of the conus medullaris, or fifth ventricle, is rare in adults. When symptomatic, surgical decompression has been advised as the primary option, although the literature on surgical treatment is sparse. This study presents the first reported case of the usage of spinal cord stimulation to manage functionally limiting pain resulting from a fifth ventricle.

Methods: A 72 year old female presented with imbalance and painful paresthesias in her lower extremities. Magnetic resonance imaging of the lumbar spine revealed a fifth ventricle, which was initially followed with serial imaging over a year. Despite stable imaging, her symptoms progressed and became functionally limiting. She underwent a two-step process, including a typical stimulation trial period followed by permanent implantation. Two 1x8 Vectris SureScan compact leads (Medtronic, USA) were placed in a staggered configuration covering T11, T12, and L1. Programming of electrodes over L1 provided her best coverage with an amplitude of 3.0mA, a pulse width of 100µs, and a frequency of 800Hz. Pain relief was measured by a percent increase or decrease, based on the patients pain level before and after the procedure, according to the standard spinal cord stimulation trial process.

Results: The trial was successful with the patient reporting over 50% relief. At one month and three-month follow up after permanent implantation, the patient reported 100% coverage of her painful paresthesias. Her imbalance was not improved. Postop MRI showed stable cyst without any additional stenosis related to the stimulator. Imaging of the cyst with the tantalum RF shielded MRI compatible leads was satisfactory, as these leads do not produce imaging artifact.

Conclusion : This study is the first to describe the technique, imaging characteristics, and programming specifics in the utilization of spinal cord stimulation to successfully control neuropathic pain resulting from a symptomatic fifth ventricle. Further research is required to understand the ultimate utility and long-term results of such treatment.