RESUMEN
The course of the facial nerve (FN) has been extensively investigated in patients with vestibular schwannomas (VSs). FN running dorsally to the tumor capsule accounts for less than 3% of the cases. Diffusion tensor imaging (DTI)-based fiber tracking helps to preoperatively identify the FN. During surgery, a higher risk of injury is associated with the dorsal location of the FN. The authors demonstrate the nuances and tricks to identify and preserve a dorsal displaced FN during resection of a large VS, T3b according to the Hannover classification, through the retrosigmoid-transmeatal approach. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2182.
RESUMEN
MATERIAL AND METHODS: A case of 60-year-old woman with idiopathic syringomyelia and progressive myelopathy by dorsal arachnoid web is discussed. One focal indentation along the dorsal surface of the spinal cord at the T3 vertebral body level revealed the scalpel sign, a radiologic entity diagnostic of a dorsal thoracic arachnoid web. RESULTS: T2-T3 laminectomy for the resection of dorsal arachnoid band was performed. Careful sectioning of the web resulted in visual apparent relief of the compression and good functional recovery. CONCLUSION: In patients with presumed idiopathic syringomyelia, imaging studies should be closely inspected for the presence of transverse arachnoid web. This extramedullary transverse band of arachnoid tissue extends to dorsal surface of the spinal cord, resulting in mass effect and dorsal indentation, known as scalpel sign because of its apparent resemblance to a scalpel on sagittal imaging. Early diagnosis with early intervention may benefit greatly patients. Surgical resection of transverse arachnoid web is a minimally invasive procedure with low morbidity, and can result in resolution of syringomyelia and improvement in neurological function.
