2025 American Academy of Neurology Abstract Website

Objective:

Arachnoid web of the spine is a rare spinal cord lesion that poses diagnostic challenges due to subtle imaging findings. It presents as an intradural extramedullary band of arachnoid tissue extending to the pial surface of the spinal cord, resulting in a focal dorsal indentation. This web typically occurs in the upper thoracic spine and may create a distinctive "scalpel" sign on imaging.

Background:

A 58-year-old man with no significant medical history presented with difficulty walking and right leg weakness for one year, worsening over the past two months. Neurological examination revealed power in the right leg at 3/5 and 4/5 in the left leg, with exaggerated deep tendon reflexes in both lower limbs and normal findings in the upper limbs.

MRI of the spine showed a small syrinx at the T4 vertebral level on the right side, along with a sharp dorsal indentation of the cord and widening of the subarachnoid space below this level. This appearance resembled a surgical scalpel. Contrast-enhanced images showed no meningeal enhancement, and the brain MRI was normal.

Design/Methods:

N/A

Results:

Due to progressive symptoms, the patient underwent surgery, which included a dorsal laminectomy from T3 to T7, releasing the arachnoid web and adhesions. Histological examination of the resected specimen revealed epithelial cells and fibrous tissue, with no inflammatory or neoplastic lesions. The patient's symptoms gradually improved, and a repeat MRI five months later showed resolution of the intramedullary signal abnormality.

Conclusions:

Thoracic arachnoid web is a rare condition that can have severe neurological consequences if untreated. Early recognition and careful evaluation of radiological findings are crucial for timely diagnosis. Syringomyelia without an identifiable cause, along with the "scalpel sign," is key to diagnosis. Surgical intervention is the only curative treatment and typically yields favorable outcomes.