SYMPTOMATIC TONSILLAR ECTOPIA

Objective-To determine if slight descent of the cerebellar tonsils (< 5 mm below the foramen magnum; tonsillar ectopia) may cause surgically treatable symptomatology. Methods-A consecutive series of nine sympto matic patients with tonsillar ectopia seen between December 1990 and M arch 1993 are reported on. The same number of age and sex matched cont rols were selected at random from outpatients. Twelve asymptomatic sub jects with tonsillar ectopia were found among 5000 people between Janu ary 1991 and March 1996. Diagnosis of tonsillar ectopia was based on m idsagittal MRI. Results-Patients presented mainly with chronic intract able occipital dull pain, vertigo, and dysequilibrium. In all patients MRI showed normal brain structure except for tonsillar ectopia (-2.9 (SD 0.8) mm), which has historically been thought to be of no clinical relevance. In the control group the tonsillar position was +2.1 (SD 2 .8) mm (p<0.01). Neurotologically abnormal findings were detected with a monaural speech integration test (100%), eye tracking test (56%), o ptokinetic nystagmus test (89%), and visual suppression test (67%) whi ch strongly suggested a CNS lesion. In accordance with the results of MRI and precise neurotological examination, posterior fossa decompress ion surgery was carried out, followed by improvement of preoperative s ymptoms and less severity of neurotological abnormalities in all patie nts. Conclusion-Tonsillar ectopia could cause neurological symptoms in small populations, which were surgically treatable. Neurotological as sessment was necessary to verify the aetiological relation between ton sillar ectopia and various symptoms.