Growth of Lumbosacral Perineural (Tarlov) Cysts: A Natural History Analysis.

Tarlov cysts (TC) are commonly found spinal perineural cysts. Symptomatic TCs are rare, however, and there is no consensus on their pathogenesis and optimal management.To characterize cyst growth in patients with symptomatic TCs.This is a retrospective cohort study of 28 subjects, evaluated for symptomatic TCs (2011-2017). Each of the subjects had multiple magnetic resonance imaging (MRIs) across time and was included in a natural history analysis.A total of 42 TCs were identified across the 28 subjects, of which 7 cysts (17%) across 5 subjects demonstrated growth. Across a mean follow-up of 4.7 ± 1.8 years, TCs grew at a relative rate of 2.9 ± 2.6% in the anteroposterior, 4.3 ± 3.8% in the craniocaudal, and 1.4 ± 1.4% in the transverse dimensions per year. None of the cysts decreased in size between successive MRIs. Symptoms of cerebrospinal fluid (CSF) hypotension (positional headaches) were positive predictors of prior cyst growth on logistic regression (P = 0.02, odds ratio = 10). A total of 2 of the 5 subjects were initially asymptomatic from their TCs, and developed symptoms during the period of cyst growth, whereas 2 others experienced worsening of their symptoms during cyst growth.We report on the growth of TCs, which is consistent with a widely-held theory that hydrostatic and pulsatile forces of CSF along with a ball-valve phenomenon allow for continuous dilation of TCs.