Inner Ear Signal Abnormalities of Adjacent Intracranial Lipochoristoma

Area of Science:

• Neuroradiology
• Neuro-oncology
• Otolaryngology

Background:

• Inner ear signal abnormalities are common with vestibular schwannoma, often linked to hearing loss.
• It remains unclear if similar signal alterations occur in other internal auditory canal (IAC) masses.
• This study investigates inner ear signal abnormalities in lipochoristomas of the IAC and cerebellopontine angle (CPA).

Purpose of the Study:

• To assess inner ear signal abnormalities in patients with lipochoristomas involving the IAC and/or CPA.
• To determine if lipochoristomas cause signal alterations in adjacent labyrinthine structures.
• To compare these findings with known abnormalities in vestibular schwannoma.

Main Methods:

• Retrospective review of MRI scans in patients with IAC/CPA lipochoristomas.
• Subjective and objective comparison of ipsilateral and contralateral labyrinthine signal intensity on FLAIR, T2 SPACE, and T2 CISS sequences.
• Consensus review by two neuroradiologists to resolve disagreements.

Main Results:

• Fourteen patients with lipochoristomas (12 IAC, 2 CPA) were analyzed.
• Abnormal labyrinthine signal was observed on FLAIR (75%) and T2 CISS (73%) sequences.
• Objective measurements showed increased ipsilateral FLAIR signal (P=.011) and decreased T2 CISS signal (P=.046).

Conclusions:

• Increased FLAIR and decreased T2 CISS signal in ipsilateral labyrinthine structures are frequent in IAC/CPA lipochoristomas.
• These signal alterations are not unique to vestibular schwannomas.
• Lipochoristomas can induce characteristic MRI signal changes in the adjacent inner ear.