gms | German Medical Science

Objective: Overshunting associated myelopathy (OSAM) is a rarely described condition, with only few reported cases. Many of them are misdiagnosed as cervical stenosis. This normally leads into worsening conditions. With this series we want to sensitize to this pathology, outline the clinical and radiological characteristics and propose treatment options.

Methods: Between 2014 and 2019 we treated four patients with overshunting associated myelopathy. We report their clinical findings, imaging and treatment.

Results: All four patients had a shunt dependent hydrocephalus and were admitted due to a progressive myelopathy. All underwent cervical MRI with contrast and cranial MRI or CT, two of them got a venous CTA. Imaging demonstrated enlarged epidural venous vessels and compression of the spinal cord. The ventral dura was thickened and irregular. Pat. 1 was initially misdiagnosed and treated with decompression of C1-C2. Later an adjustable shunt-valve was implanted followed by pressure adjustment. Pat. 2 underwent surgery for multilevel cervical stenosis and got an adjustable shunt-valve followed by pressure adjustment. Pat. 3 and 4 were treated with valve-adjustment.

Conclusion: Chronic over drainage may lead to an enlargement of the epidural venous plexus, according the Monroe-Kellie doctrine, causing cord compression and progressive myelopathy. Complex spinal surgery could be avoided in most cases by recognizing radiological patterns and valve-implantation/-adjustment. Wherefore a sensitization for this condition is important, as prevalence of OSAM may be underestimated and often misdiagnosed.