Dorsal thoracic arachnoid webs are due to a deformity in the formation of arachnoid membrane in the spinal arachnoid space. These webs usually occur in the upper thoracic spine and are viewed on imaging as a pathogonomic 'scalpel' sign because of the resemblance on sagittal MRI to a surgical scalpel. We describe a case of a patient with a neuropathic pain presentation. After MR imaging, a focal dorsal indentation of the upper thoracic spinal cord at the T3-T4 level with the scalpel sign was found. This sign indicates that the patient's neuropathic pain was caused by the dorsal thoracic arachnoid web.
Keywords: Arachnoid web; dorsal thoracic arachnoid web; neuropathic pain; scalpel sign.
© The Author(s) 2016.