Electromyographic Abnormalities Associated with Symptomatic Sacral Tarlov Cysts

Tarlov, or perineural cysts (TC) are commonly overlooked as a cause of sacroischialgia and urogenital and bowel problems. TC can be seen on MRI, but are often considered asymptomatic. This is especially true for smaller cysts. Moreover, there are only few diagnostic characteristics that can be used to confirm that the cysts are the cause of the symptoms. As a consequence, a lot of controversy remains regarding the clinical importance of TC. Because of this underdiagnosed condition, patients often suffer for several years from unrecognized chronic neuropathic pain and neurological conditions. In this paper, case reports of three patients with giant and smaller symptomatic sacral cysts are presented, in which electromyographic testing was performed in order to demonstrate nerve damage. We conclude that electromyography of the sacral nerve roots can be a reasonable tool for the diagnosis of symptomatic TC, as well as for the differentiation from other pathological entities causing sacroischialgia. Moreover, using electromyography it was also documented that smaller cysts of less than 1 cm can cause nerve damage. Therefore incidence of symptomatic TC may be higher than initially thought.status: publishe