High Prevalence of Small-Fiber Neuropathy in Patients with Tarlov Cysts: Toward a More Comprehensive Clinical Understanding.

Purpose: To explore the prevalence of small-fiber neuropathy (SFN) and the clinical characteristics of patients with Tarlov cysts (PTCs), focusing on symptoms related to SFN and increased cerebrospinal pressure.

Patients and methods: In this retrospective study, 126 surveys assessing symptoms in women (30-69 years) with Tarlov cysts (TCs) ≥ 7 mm seeking treatment for chronic back, pelvic or leg pain and skin biopsy results from 75 patients assessing intraepidermal nerve fiber density (IENFD) were reviewed.

Results: IENFD < 5th percentile was documented in 80% of PTCs according to the normative reference data of Collongues et al and 72% according to the worldwide dataset of Lauria et al Questionnaires revealed high incidences of neuropathic pain (80%), allodynia (76%), pain while sitting (93%), anal sphincter (11%) and urinary sphincter (66%) problems, persistent genital arousal (27%), and restless legs (54%). Autonomic dysfunctions included early satiety (41%), bladder (93%) and bowel (88%) dysfunction, increased sweating (51%), and Raynaud's phenomenon (45%). Other symptoms potentially associated with increased cerebrospinal fluid pressure (CSFP) were headaches (57%), fatigue (86%), cognitive issues (86%), and pulsatile tinnitus (59%).

Conclusion: This study revealed a high prevalence of SFN in PTCs (72-80%). Although the TCs may not cause radicular pain in the corresponding dermatomes directly, individuals with TCs frequently report a range of symptoms that have previously been linked to symptomatic TCs, including bladder, bowel, sphincter, and sexual symptoms, as well as local pain. Additionally, seemingly unrelated symptoms, such as headaches, fatigue, cognitive difficulties, neuropathic pain localized in other parts of the body, and autonomic dysfunctions, are commonly reported. These symptoms may be associated with elevated CSFP within the nerve root sheath. Elevated pulsatile CSFP underlies the formation of TCs at the dorsal root ganglion and may gradually contribute to small-fiber dysfunction by irritating, compressing and damaging small nerve fibers within the dorsal root ganglion.