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 χ 2 , Pearson χ 2 , 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.
Pudendal neuralgia is a painful and often chronically debilitating neuropathic condition involving the pudendal nerve dermatome, affecting an estimated 1% of the population. The pudendal nerve is derived from sacral roots S2–S4 and travels through an anatomically narrow interligamentous space, Alcock’s canal, and the fibro-osseous canal. The nerve branches into the dorsal nerve of the penis/clitoris, the perineal nerve, and the inferior anal nerve. Etiology is often related to entrapment of the nerve or branches by the surrounding pelvic floor muscles or the sacral ligaments. Additionally, postsurgical neuralgia can occur owing to direct trauma or placement of medical devices such as mesh. Patients typically present with symptoms ranging from discomfort or numbness to sharp, intense, burning neuropathic pain in characteristic territories along the nerve pathways. Female subjects can have pain located in the vulva, vagina, clitoris, perineum, and rectum, whereas male subjects may report pain in the scrotum, perineum, and rectum.
Why was this study conducted?
To evaluate the prevalence of S2–S4 Tarlov cysts at the pudendal nerve origin in patients with pudendal neuralgia, and establish association of patient symptoms with location of Tarlov cyst.
Key findings
Clinical and radiologic assessment between laterality of symptoms and Tarlov cysts failed to demonstrate concordance in 31 of 38 (81.6%) patients. No significant association was found between cyst size and pain laterality, cyst volume and pain location, or cyst size and unilateral vs bilateral pain.
What does this add to what is known?
The findings in this study suggest Tarlov cysts are most likely not the etiology of pudendal neuralgia, though it is possible they could have similar pathogenesis. These negative findings should be taken into consideration before pursuing invasive treatment with additional risks, which may have limited to no benefit for affected patients.
Diagnosis of pudendal neuralgia is predominantly clinical. According to the Nantes criteria, which is a set of 5 essential diagnostic criteria, the pain must be (1) in the prior mentioned territories and (2) worsened by sitting, with (3) lack of sensory loss, (4) lack of nighttime awakening from pain, and (5) anesthesia from pudendal nerve block. Other complementary criteria and associated signs include quality of pain described as stabbing or shooting, allodynia, worsening pain throughout the day, and pain triggered by defecation or coitus. Treatment is initially conservative and starts with oral neuroleptics, muscle relaxants, and nonsteroidal anti-inflammatory drugs. Local muscle relaxant suppositories have been found to be superior to their oral counterparts, and of critical importance is early concomitant pelvic physical therapy. Many patients have intractable pain, and computed tomography (CT)-guided nerve blocks and surgical decompression may be an option for these refractory cases.
Tarlov cysts have been reported in the literature as another potential cause of chronic lumbosacral and pelvic pain. These cysts are cerebrospinal fluid (CSF)-filled dilations of the perineural space with walls consisting of vascularized connective tissue and spinal nerve root fibers. Diagnosis can be made with CT, magnetic resonance imaging (MRI), or flow-sensitive magnetic resonance sequences that can detect the communication between the cyst and subarachnoid space.
Notably, Tarlov cysts 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. However, literature has been inconsistent on the clinical relevance of the cysts and if they are responsible for symptoms. Some studies have found that Tarlov cyst presence itself was asymptomatic and attributed the pain to another etiology discovered at the same spinal level. Others have hypothesized differently, and described microsurgical techniques on the cysts with high resolution of pain. The reported surgical techniques include laminectomies with microsurgical exposure and/or imbrication and paraspinous muscle flap closure, sacral canal unroofing and cyst excision, and CT-guided percutaneous fibrin glue injections, among others. The purpose of this study is to investigate the prevalence of Tarlov cysts in patients diagnosed with pudendal neuralgia, and to evaluate the association of pain laterality with Tarlov cyst locations.
Methods
A retrospective case series chart review was performed on patients diagnosed with pudendal neuralgia seen in a single academic chronic pelvic pain center from January 2010 to November 2012. Patients were diagnosed with pudendal neuralgia clinically by pelvic pain specialists utilizing the validated Nantes criteria, and none met exclusion criteria. The Nantes criteria are composed of 5 essential components: (1) pain in the anatomical territory of the pudendal nerve; (2) worsened by sitting; (3) the patient is not woken at night by the pain; (4) no objective sensory loss on clinical examination; (5) positive anesthetic pudendal nerve block. There are no pathognomonic criteria, but the combination is most suggestive of the disease. Published exclusion criteria include purely coccygeal, gluteal, or hypogastric pain; exclusively paroxysmal pain; exclusive pruritus; or presence of imaging abnormalities able to explain the symptoms.
Institutional Review Board approval was obtained, and informed consent was deemed unnecessary owing to absence of patient identifiers and the retrospective nature of the study. For a practice specializing in treating pudendal neuralgia, protocol directs all pelvic pain patients to receive a pelvic MRI. During this time, pelvic surgeon specialists referred a total of 242 patients diagnosed with pudendal neuralgia for pelvic MRI. Neuroradiologists performed a dedicated MRI review specifically for all potential causes of pelvic pain and evaluated for presence of Tarlov cysts. The dedicated pelvic pudendal MRI protocol was composed of sequences allowing to evaluate for presence vs absence of scars; dilated vessels along the course of the pudendal neurovascular bundles; pelvic floor prolapse; female pelvic organ pathology (ie, endometriosis, uterine fibrosis, adenomyosis, adnexal cystic lesions); and gastrointestinal (ie, rectal cancer, diverticulitis), urologic (ie, urethritis), and musculoskeletal pelvic pathology (ie, hamstring tendonosis). The presence of other focal or central pain syndromes or symptoms did not exclude the diagnosis of pudendal neuralgia. Among those with demonstrable cysts, subsequent imaging data of the laterality, level, and size of the Tarlov cyst were collected on 39 of the patients with pudendal neuralgia. Pain location, laterality, and comorbid conditions were collected for all but 1 patient with an incomplete medical record. Tarlov cyst features were thus correlated with clinical site of symptoms for the subset of 38 patients with pudendal neuralgia and complete records.
Statistical analysis was performed using χ 2 , Pearson χ 2 , and Fisher exact tests, utilizing a P value of less than .05 as the threshold for concluding a significant difference exists. Analyses were performed in SAS v9.4 (SAS Institute, Cary, NC).
Results
Of the 242 patients identified with pudendal neuralgia, average age was 51.3 (range, 24–83) years, with 188 (77.7%) women and 54 (22.3%) men. Thirty-nine (16.1%) patients demonstrated at least 1 sacral Tarlov cyst, with a total of 50 Tarlov cysts identified in the entire patient cohort. Patient demographics, presenting signs/symptoms, and comorbid conditions for the Tarlov cyst population are presented in Table 1 , and Tarlov cyst features are presented in Table 2 a and 2b . The majority of the Tarlov cysts were found at the S2–S3 level (32/50 or 64%). One patient had a Tarlov cyst outside the pudendal nerve distribution (L5–S1). Five patients (13%) had Tarlov cysts at multiple sacral levels. In our group of patients, Tarlov cysts were predominantly moderate (1–2 cm) and small (<1 cm) in size, representing 50% and 44% of the total Tarlov cysts, respectively. The diameter of the largest cyst was 5.1 cm and the smallest was 3 mm.
| All (n = 39) | Male (n = 5) | Female (n = 34) | |
|---|---|---|---|
| Age, years | 54.7 ± 12.1 | 53.4 ± 8.2 | 54.9 ± 12.6 |
| Symptoms, n (%) | Subset (n = 38) | (n = 5) | (n = 33) |
| Bladder | 3 (7.9%) | 0 | 3 |
| Buttock | 3 (7.9%) | 0 | 3 |
| Perineum | 11 (28.9%) | 4 | 7 |
| Rectum | 15 (39.5%) | 1 | 14 |
| Clitoris | 5 (13.2%) | — | 5 |
| Labia | 6 (15.8%) | — | 6 |
| Vagina | 19 (50.0%) | — | 19 |
| Penis (glans) | 2 (5.3%) | 2 | — |
| Scrotum | 3 (7.9%) | 3 | — |
| Comorbid conditions, n (%) | |||
| Interstitial cystitis | 4 (10.5%) | — | 4 (10.5%) |
| Pelvic floor tension myalgia | 19 (50%) | 2 | 17 |
| Pelvic organ prolapse a | 7 (18.4%) | — | 7 (18.4%) |
| Persistent genital arousal | 2 (5.3%) | — | 2 (5.3%) |
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
