Neurophysiologic, audiometric and vestibular function tests in patients with hyperostosis cranialis interna

Area of Science:

• Neurology
• Genetics
• Otolaryngology

Background:

• Hyperostosis cranialis interna (HCI) is a rare autosomal dominant disorder.
• It causes skull base and calvaria thickening, leading to cranial nerve deficits via neuroforamina stenosis.

Purpose of the Study:

• To evaluate the diagnostic utility of neurophysiological, audiometric, and vestibular tests in HCI patients.
• To correlate test results with the clinical progression of the disorder.

Main Methods:

• Ten HCI patients and 13 unaffected family members underwent comprehensive testing.
• Tests included visual evoked potentials (VEPs), blink reflex, masseter reflex, audiometry, otoacoustic emissions, brainstem evoked response audiometry (BERA), and electronystagmography.

Main Results:

• VEPs, blink reflex, and masseter reflex showed low sensitivity (25-37.5%) due to the disease's bilateral nature.
• Hearing impairments and prolonged BERA latency (inter-peak latency I-V) were observed in 60-70% of patients, indicating nerve encroachment.
• 50% of patients exhibited vestibular abnormalities; otoacoustic emissions were unaffected as the cochlea is spared.

Conclusions:

• Audiometry, BERA, and vestibular tests are recommended for monitoring vestibulocochlear nerve function in HCI.
• VEPs are valuable for optic nerve assessment alongside imaging and ophthalmologic exams.
• Routine use of blink and masseter reflexes is not advised for HCI evaluation.