Somatosensory evoked potentials and cerebrospinal fluid flow in Chiari malformation

Abstract

AimMany studies reported that the degree of tonsillar herniation does not correlate with the severity of symptoms in Chiari Malformation Type 1 patients. The aim of this study is to investigate the relationship between tonsillar herniation, cerebrospinal fluid (CSF) flow, and somatosensory evoked potentials (SEP) in Chiari Malformation Type 1 patients. MethodsWe retrospectively reviewed 27 patients with Chiari Malformation treated in our clinic. There were 7 men (25.3%) and 20 women (74.1%), mean age 38 years (range 15–62). Patients were grouped by tonsillar ectopia (0–5 mm vs >5 mm). CSF flow abnormalities were assessed with phase contrast MRI, and SEP abnormalities were evaluated in upper and lower extremities. Linear and angular morphometric measurements of clivus, supraocciput, cerebellum hemisphere, McRae line, Twinning line, tentorium Twinning angle, Welcher basal angle, and Boogaard angle were taken. Surgical history, presence of syrinx, hydrocephalus, basilar invagination, and platybasia were recorded. ResultsFourteen patients (51.9%) had 0–5 mm tonsillar ectopia, 13 (48.1%) had >5 mm. CSF flow abnormality was observed in 13 patients (48.1%), SEP abnormality in 6 patients (22.2%). A significant relationship was found between CSF flow disturbance and degree of tonsillar ectopia (P = .038), and between CSF flow disturbance and SEP abnormality (P = .016). Five patients (18.5%) underwent surgery, all had tonsillar ectopia >5 mm. Platybasia was associated with higher rates of CSF flow and SEP abnormalities. ConclusionCSF flow disturbances in Chiari symptomatic patients indicate a hypoplastic posterior fossa. Morphometric and functional assessments, including SEP, can aid in diagnosis and surgical decision-making, and may be used for prognostic evaluation and follow-up in incidental asymptomatic cases. Future studies with larger populations and sleep disturbance analysis are warranted.

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