Large- and Small-Fiber Neuropathy in Patients with Tarlov Cysts

Abstract

Purpose Tarlov cysts (TCs) are dilated nerve root sheaths originating from increased cerebrospinal pressure. Patients with TCs often complain of neuropathic pain and paresthesia. The aim of this study was to retrospectively review intraepidermal nerve fiber density (IENFD) and electrodiagnostic (EDX) data from TC patients. Patients and Methods Lower leg skin biopsy results and EDX data from the L2–S4 myotomes of patients with lumbar or sacral TCs ≥8 mm were retrieved from a database of a physical medicine clinic. Patients with compressive pathology, diabetes mellitus and chemotherapy were excluded. Results IENFD data from 17 patients and EDX data from 24 patients with TCs ≥8 mm were available. The mean age was 47 ± 10y, and 83% were women. In 82% of patients, the IENFD was below the 5th percentile by age and sex. EDX showed increased Hoffmann reflex latencies in 25%, increased anal reflex latencies in 95%, and a patchy distribution of neurogenic motor unit potentials in 100%. More than 50% of needle EMG abnormalities appeared in myotomes unrelated to the location of the TCs. Conclusion Small- and/or large-fiber neuropathy was documented in a significant proportion of patients with TCs. The novel findings may add to the understanding of the mechanisms involved in symptomatic TCs. We propose that pathologically elevated cerebrospinal fluid pressure not only dilates some of the nerve root sheaths to form TCs but also potentially damages axons in nondilated nerve root sheaths and neurons in the dorsal root ganglia.

Management of Tarlov cysts: an uncommon but potentially serious spinal column disease—review of the literature and experience with over 1000 referrals

“…Abnormal neurophysiological findings were also reported in larger cohort studies of patients referred to a physical medicine outpatient clinic: a 30-patient cohort [85] and a later 31-patient cohort [86]. Nerve conduction studies in the 30-patient cohort were abnormal for sural nerves, S1 Hoffman-reflex latency, and the ano-anal reflex with almost all abnormalities corresponding with dermatomal pain or paresthesia [76,85].…”

“…Nerve fiber neuropathy was evaluated in 31 patients with symptomatic Tarlov cysts [ 86 ]. Small fiber neuropathy was evaluated with lower leg skin biopsies to assess intraepidermal nerve fiber density, and the majority of patients with biopsy samples were below the 5% percentile of age-sex-matched reference values for this nerve damage.…”

“…Several investigators [83][84][85][86] employed electrodiagnostic studies, both nerve conduction and needle electromyography (EMG) to assess axonal or nerve root injury associated with Tarlov cysts and correlate with sacral nerve root damage (Table 2). The sural nerve was often the target nerve in the studies as it is composed mainly of fibers originating mainly from the S1 and S2 sacral roots where Tarlov cysts tend to localize.…”

Advances in the Diagnosis and Treatment of Sacral Cysts

“…Paulsen [4] put forward the theory of "ball valves", suggesting that, when people do coughing, strenuous exercise or Valsalva, abdominal pressure increases, which will cause an increase in intracranial pressure, which will open the hidden space between the nerve membrane and the endothelium to become more open, thus creating a unidirectional valve, Paulsen [4] proposed the "ball valve" theory, suggesting that when people cough, exercise strenuously or Valsalva, the abdominal pressure increases, which will increase the intracranial pressure, which will open up the hidden space between the nerve membrane and the endothelium, making it more open, thus forming a unidirectional flap, which, if continued, will increase in size until it presses on the peripheral nerves, causing serious neurological disorders. Hulens M [5] analyzed 17 patients and suggested that pathologically elevated cerebrospinal fluid pressure would not only dilate some nerve root sheaths to form sacral cysts, but also damage axons in the undilated nerve root sheaths and neurons in the dorsal root ganglia. Potts MB et al [6] found that if patients suffered trauma to the sacrococcygeal region in their daily lives, it would cause rupture of the blood vessels between the outer membrane of the nerve root and the fasciculus to hemorrhage, resulting in injurious changes.…”