Electromyographic Abnormalities Associated with Symptomatic Sacral Tarlov Cysts

Abstract

Tarlov or perineural cysts (TC) are commonly overlooked as a cause of sacral and ischial pain, 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 article, case reports of three patients with giant and smaller symptomatic sacral cysts are presented, in which electromyographic testing was performed to demonstrate nerve damage. We suggest 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 sacral and ischial pain. Moreover, using electromyography it was also documented that smaller cysts of < 1 cm can cause nerve damage. Therefore incidence of symptomatic TC may be higher than initially thought.

Electromyography and A Review of the Literature Provide Insights into the Role of Sacral Perineural Cysts in Unexplained Chronic Pelvic, Perineal and Leg Pain Syndromes

“…The pain was usually not in one dermatome, but in several dermatomes at the same time. Moreover, the most severe pain was not always on the side of the largest cyst [8]. To date, the reason for this lack of correlation is not clear.…”

“…This is because of the fragility of the tissues and the elevated pressure in the spinal canal [10]. Finally, a high frequency of headaches might also reflect increased pressure in the cerebrospinal canal [1,2,8,11,18,33].…”

“…Many physicians are therefore unaware that "sacral symptomatic Tarlov cysts" (STCs) are a well-defined clinical entity that includes debilitating pelvic, perineal and leg pain and urogenital and bowel disturbances. STCs are easily identified when a comprehensive history is obtained [2,5,7,8].…”

“…Because this pathology is systematically overlooked, several authors have suggested that the incidence of STCs is significantly underestimated [2,5,[8][9][10][11][12][13][14][15][16].…”

An unusual complication of sacral nerve root injury following bone marrow harvesting: a case report

“…Hoffmann reflex, pudendal evoked potential were within normal limits. Electromyography (EMG) showed abnormal spontaneous activities, which are denervation potentials, in the S2-innervated intrinsic foot muscles and the S1-S2 nerve root innervated muscles such as the soleus, gastrocnemius, and lumbar paraspinalis muscle (Table 1) [7–9]. The amplitude of the abnormal spontaneous activities were about 100 μV, indicating that the development of muscle membrane instability following neural injury occurred within 1 month [10] (Fig.…”