Abnormal SEP reflects dysfunction of the medial lemniscus and posterior
cervical cord. These structures are likely to be affected in Chiari
malformation. Therefore, SEP abnormalities may provide valuable information in
patients with CM. However, the consistency of SEP abnormality or normality with
the damage is a matter of research. Knowing whether median nerve somatosensory
evoked potential (SEP) is useful in revealing subclinical damage in patients
with Chiari malformation is important in the treatment and follow-up plan of
the disease. The aim of this study was to investigate the relationship between
median nerve SEP values and the severity of cerebellar ectopia in patients with
Chiari type 1 malformation. Median nerve SEP values were obtained from 30 healthy
individuals and 146 individuals with Chiari malformation. The cerebellar
ectopia degree and McRae line length were measured. SEP values were not
significantly different between groups. The McRae line was found to be
significantly shorter in the control group than in the Chiari malformation
group (p = 0.031). There was no correlation between the degree of cerebellar
ectopia and the length of the McRae line (r = 0.002, p = 0.979). Neither
cerebellar ectopy degree nor McRae line length had a relationship with SEP values
(r = -0.153, p = 0.066; r = -0.056, p = 0.500, respectively). There was no
difference in cerebellar ectopy degree or SEP values between the groups with
cerebellar ectopy with and without a syrinx (p = 0.899; p = 0.080,
respectively). Likewise, McRae line length was not found to be related to the
presence of a syrinx (p = 0.139). Median nerve SEP examination was not
beneficial for diagnosing asymptomatic-oligosymptomatic Chiari malformation as
a subclinical injury, whether accompanied by syringomyelia or not.
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