Have Cranio-Vertebral Junction Anomalies Been Overlooked as a Cause of Vertebro-Basilar Insufficiency?

Abstract

A prospective controlled study using single photon emission computed tomography (SPECT) to assess cerebellar perfusion in a cohort of 19 patients with congenital cranio-vertebral junction (CVJ) anomalies, with or without vertebro-basilar insufficiency (VBI). To correlate symptoms of VBI with the presence of posterior circulation ischemia in patients with congenital CVJ anomalies, using technetium 99m ethylene cystine dimer SPECT. Patients with VBI are rarely investigated for CVJ anomalies, despite the fact that a significant number of patients with congenital CVJ anomalies has VBI. There are also no studies quantifying outcome of surgical interventions, such as like occipito-cervical fusion, in patients with VBI and CVJ anomalies. There were 19 consecutive patients with congenital CVJ anomalies who were scheduled for combined transoral odontoidectomy and occipito-cervical fusion were included in the study. Technetium 99m ethylene cystine dimer brain SPECT and clinical assessment of all patients was performed in the preoperative period and at 4 weeks after surgery. Before surgery, patients were divided into 2 groups depending on the clinical findings: (1) symptomatic group, consisting of 12 patients having features suggestive of VBI (drop attacks, episodic vertigo, visual disturbances and dysarthria); and (2) control group, consisting of 7 patients without symptoms of VBI. SPECT showed decreased cerebellar perfusion in 75% (n = 9) of patients in the symptomatic group compared to 14% (n = 1) in the control group before surgery (Fisher exact 2-tailed test, P = 0.019). Following surgery, 8 patients (88.9%) in the symptomatic group and none in the control group had improvement in cerebellar perfusion. Two patients in the symptomatic group who had meningitis develop during the postoperative period had a decrease in cerebellar perfusion on follow-up SPECT. Clinically, all patients with improvement in cerebellar perfusion had improvement in the symptoms of VBI at 1 month of follow-up. A significant number of patients with congenital CVJ anomalies who have symptoms of VBI develop have decreased cerebellar perfusion shown by SPECT. Rigid internal fixation of the CVJ may alleviate symptoms and improve posterior circulation in some of these patients.