Abstract
Treatment of Chiari malformation can include suboccipital decompression with resection of one cerebellar tonsil. Its effects on ocular motor and cerebellar function have not yet been systematically examined. To investigate whether decompression, including resection of one cerebellar tonsil, leads to ocular motor, vestibular, or cerebellar deficits. Ten patients with Chiari malformation type 1 were systematically examined before and after (1 week and 3 months) suboccipital decompression with unilateral tonsillectomy. The work-up included a neurological and neuro-ophthalmological examination, vestibular function, posturography, and subjective scales. Cerebellar function was evaluated by ataxia rating scales. Decompression led to a major subjective improvement 3 months after surgery, especially regarding headache (5/5 patients), hyp-/dysesthesia (5/5 patients), ataxia of the upper limbs (4/5 patients), and paresis of the triceps and interosseal muscles (2/2 patients). Ocular motor disturbances before decompression were detected in 50% of the patients. These symptoms improved after surgery, but five patients had new persisting mild ocular motor deficits 3 months after decompression with unilateral tonsillectomy (i.e., smooth pursuit deficits, horizontally gaze-evoked nystagmus, rebound, and downbeat nystagmus) without any subjective complaints. Impaired vestibular (horizontal canal, saccular, and utricular) function improved in five of seven patients with impaired function before surgery. Posturographic measurements after surgery did not change significantly. Decompression, including resection of one cerebellar tonsil, leads to an effective relief of patients' preoperative complaints. It is a safe procedure when performed with the help of intraoperative electrophysiological monitoring, although mild ocular motor dysfunctions were seen in half of the patients, which were fortunately asymptomatic.
Highlights
Chiari malformation comprises a group of pathological entities characterized by the presence of anatomical deformities of the cerebellum and brainstem
Cerebellar function was evaluated by ataxia rating scales, namely, the Scale for the Assessment and Rating of Ataxia (SARA) [10] and the Spinocerebellar Ataxia Functional Index (SCAFI) [11]
Ten patients with a Chiari malformation type 1 confirmed by MRI (6 females, mean age 37 years, range 18–57) were included in this study
Summary
Chiari malformation comprises a group of pathological entities characterized by the presence of anatomical deformities of the cerebellum and brainstem. Current treatment includes a decompression of the suboccipital region to enlarge the diameter of the foramen magnum and resection of the posterior arch of C1. Sufficient decompression of the brainstem is more likely when the arachnoid and the tonsils are manipulated [1, 4] (details in Data Sheet S1 in Supplementary Material). Data about clinical outcome after surgical treatment vary due to different surgical methods, patient cohorts, and symptoms. Ocular motor dysfunctions improved in 75–100% of patients [5,6,7]. Treatment of Chiari malformation can include suboccipital decompression with resection of one cerebellar tonsil. Its effects on ocular motor and cerebellar function have not yet been systematically examined
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have