Remote Paraparesis due to a Traumatic Extradural Arachnoid Cyst Developing 2 Years after Brachial Plexus Root Avulsion Injury: Case Report and Review of the Literature.

Traumatic extradural arachnoid cyst is a rare entity. However, late appearance of paraparesis due to formation of an extradural arachnoid cyst as a sequel of brachial plexus injury is extremely rare and the literature regarding this issue is scarce revealing only 11 cases. Herein, we report a patient with delayed progressive spastic paraparesis appearing after a multilevel brachial plexus root avulsion injury where imaging revealed formation of a large traumatic extradural arachnoid cyst at the cervicothoracic region.