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  • Thinning of Skull Anatomy in IIH

    By Lynda Seminara
    Selected by Prem S. Subramanian, MD, PhD
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    Journal Highlights

    Journal of Neuro-Ophthalmology
    Published online Feb. 15, 2022

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    Barke et al. set out to determine if there is an independent relationship between idiopathic intracranial hy­pertension (IIH) and thinning of the skull base or calvarium. They found that both structures were narrower in patients with IIH and that patients’ obesity was unrelated to changes in either area.

    In this retrospective case-control study, each of 63 patients with an IIH diagnosis (case) was matched by age, sex, and race to a patient with a head­ache diagnosis (control). All participants underwent computed tomography of the head, maxillofacial region, or orbits within three months of their diagnosis. Skull-base thickness was determined by the height of the auditory canal in the coronal plane. Calvarial thickness was measured just anterior to the foramen rotundum in the same plane. Zygoma thickness was chosen as the imaging control because it is not affected by intracranial force.

    Each study cohort included 61 females and two males. The mean age was 30.7 years in those with IIH and 32.3 years in controls. There were 24 Whites, 23 Blacks, one Asian, and 15 who described their race as “other” in each group. Obesity was more common in patients with IIH (95% vs. 37% of controls).

    All participants with IIH and 13 controls underwent lumbar puncture. The average opening pressures were 40.5 ± 15.6 cm H2O in patients with IIH and 19.5 ± 8.5 cm H2O in those from the control group. Visual acuity did not differ significantly between patients with IIH (logMAR 0.22 ± 0.45) and controls (logMAR 0.09 ± 0.30). Those with IIH had a thinner skull base (mean, 4.17 ± 0.94 mm vs. 5.05 ± 1.12 mm; p < .001) and calvarium (mean, 1.50 ± 0.50 mm vs. 1.71 ± 0.61 mm; p = .024). Mean zygoma thickness was similar for the two groups (IIH, 1.18 ± 0.30 mm; control, 1.26 ± 0.35 mm; p = .105).

    Patients with IIH experienced more headache (97% vs. 74%; p = .001), pul­satile tinnitus (48% vs. 7%; p < .001), horizontal binocular diplopia (24% vs. 4%; p = .006), confrontational visual field deficit (23% vs. 2%; p = .003), and papilledema (74% vs. 0%; p < .001). A subgroup comparison of obese and nonobese patients showed no significant differences in thickness of the skull base, calvarium, or zygoma—unlike findings of previous research.

    The results suggest that IIH is inde­pendently associated with thinning of the skull base and calvarium, said the authors. They recommend investiga­tions of the pathogenesis underlying the link between IIH and these struc­tures.

    The original article can be found here.