Cranial nerve abnormalities in spontaneous intracranial hypotension and their clinical relevance

Spontaneous intracranial hypotension (SIH) is a known cause of headaches and neurologic symptoms, but the frequency of cranial nerve symptoms and abnormalities on magnetic resonance imaging (MRI) has not been well described. The purpose of this study was to document cranial nerve findings in patients with SIH and determine the relationship between imaging findings and clinical symptoms.

Patients diagnosed with SIH with pre-treatment brain MRI at a single institution from September 2014 to July 2017 were retrospectively reviewed to determine the frequency of clinically significant visual changes/diplopia (cranial nerves 3 and 6) and hearing changes/vertigo (cranial nerve 8). A blinded review of brain MRIs before and after treatment was conducted to assess for abnormal contrast enhancement of cranial nerves 3, 6, and 8. Imaging results were correlated with clinical symptoms.

Thirty SIH patients with pre-treatment brain MRI were identified. Sixty-six percent of patients had vision changes, diplopia, hearing changes, and/or vertigo. Cranial nerve 3 and/or 6 enhancement was present in nine patients on MRI, with 7/9 patients experiencing visual changes and/or diplopia (odds ratio [OR] 14.9, 95% confidence interval [CI] 2.2-100.8, p = .006). Cranial nerve 8 enhancement was present in 20 patients on MRI, with 13/20 patients experiencing hearing changes and/or vertigo (OR 16.7, 95% CI 1.7-160.6, p = .015).

SIH patients with cranial nerve findings on MRI were more likely to have associated neurologic symptoms than those without imaging findings. Cranial nerve abnormalities on brain MRI should be reported in suspected SIH patients as they may support the diagnosis and explain patient symptoms.