Evaluating the discordant relationship between Tarlov cysts and symptoms of pudendal neuralgia

Background: Pudendal neuralgia is a painful neuropathic condition involving the pudendal nerve dermatome. Tarlov cysts have been reported in the literature as another potential cause of chronic lumbosacral and pelvic pain. Notably, they are often located in the distribution of the pudendal nerve origin at the S2, S3, and S4 sacral nerve roots and it has been postulated that they may cause similar symptoms to pudendal neuralgia. Literature has been inconsistent on the clinical relevance of the cysts and if they are responsible for symptoms.

Objective: To evaluate the prevalence of S2-S4 Tarlov cysts at the pudendal nerve origin (S2-S4 sacral nerve roots) in patients specifically diagnosed with pudendal neuralgia, and establish association of patient symptoms with location of Tarlov cyst.

Study design: A retrospective study was performed on 242 patients with pudendal neuralgia referred for pelvic magnetic resonance imaging from January 2010 to November 2012. Dedicated magnetic resonance imaging review evaluated for presence, level, site, and size of Tarlov cysts. Among those with demonstrable cysts, subsequent imaging data were collected and correlated with the patients' clinical site of symptoms. Statistical analysis was performed using χ², Pearson χ², and Fisher exact tests to assess significance.

Results: Thirty-nine (16.1%) patients demonstrated at least 1 sacral Tarlov cyst; and of the 38 patients with complete pain records, 31 (81.6%) had a mismatch in findings. A total of 50 Tarlov cysts were identified in the entire patient cohort. The majority of the Tarlov cysts were found at the S2-S3 level (32/50; 64%). Seventeen patients (44.7%) revealed unilateral discordant findings: unilateral symptoms on the opposite side as the Tarlov cyst. In addition, 14 (36.8%) patients were detected with bilateral discordant findings: 11 (28.9%) had bilateral symptoms with a unilateral Tarlov cyst, and 3 (7.9%) had unilateral symptoms with bilateral cysts. Concordant findings were only demonstrated in 7 patients (18.4%). No significant association was found between cyst size and pain laterality (P = .161), cyst volume and pain location (P = .546), or cyst size and unilateral vs bilateral pain (P = .997).

Conclusion: The increased prevalence of Tarlov cysts is likely not the etiology of pudendal neuralgia, yet both could be due to similar pathogenesis from part of a focal or generalized condition.