Meningioma of the internal auditory vanal: case report

Meningiomas of the Internal Auditory Canal

OBJECTIVE

Identify and define specific preoperative and postoperative characteristics of intracanalicular meningiomas (ICMs) in order to improve their diagnosis and management, and to differentiate them from intrameatal vestibular schwannomas (IMVSs).

METHODS

Preoperative symptomatology, magnetic resonance imaging (MRI), and postoperative outcomes of 28 ICMs were analyzed. The results were compared to the literature and IMVSs treated by our group.

RESULTS

Anacusis and progressive hearing loss were more frequent in the present population than the cases reviewed (P = .0064 and P = .0001, respectively). Hearing loss affected more than 90% of the patients, with anacusis in 32.1% of the cases. Facial palsy affected 17.9% of the patients. In comparison to IMVSs, preoperative anacusis was more associated to meningiomas (P = .0037), and the facial nerve was more compromised in ICMs than IMVSs, both preoperatively (P = .0011) and at follow-up (P < .0001). According to a re-evaluation of preoperative MRIs and comparison with IMVSs, linear tumor borders, and linear morphology along the internal auditory canal wall, but not the presence of a dural tail, were significantly more present in ICMs (P = .0035, P = .0004, P = .1963, respectively). These characteristics could have led to a correct preoperative diagnosis in 61% of our cases.

CONCLUSION

Contrariwise to IMVSs, the frequent preoperative anacusis and facial palsy demonstrate the more aggressive nature of ICMs, which also carry a higher risk of postoperative facial palsy and difficulty to preserve hearing. An attentive evaluation of imaging should ease diagnosis, and asymptomatic or stable ICMs should be enrolled in a wait-and-scan protocol.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E413-E419, 2021.

Non-schwannomatosis lesions of the internal acoustic meatus-a diagnostic challenge and management: a series report of nine cases

Vestibular schwannomas (VS) are the most common lesions of cerebellopontine angle (CPA) corresponding to 76-91 % of the cases. Usually, these lesions present typical CT and MRI findings. Non-schwannomatous tumors restricted to the internal auditory meatus (IAM) are rare and their preoperative radiological diagnosis may be difficult. This article describes nine surgically treated intrameatal non-schwannomatous lesions (NSL) and reviews the literature. In the last 16 years, a total of 471 patients with diagnosis of VS were operated on in our department. Preoperatively, 42 patients had diagnosis of intrameatal schwannomas, but surgery revealed in nine cases NSL (3 meningiomas, 3 arachnoiditis/neuritis, 1 cavernoma, 1 vascular loop, and 1 arachnoid cyst). Most frequent symptoms presented by patients with NSL were hearing loss 89 % (8/9) of patients, tinnitus 78 % (7/9), and vertigo 33 % (3/9). Almost all lesions (8/9) presented MRI findings of isointense signal in T1W with contrast enhancement. The only exception was the arachnoid cyst with intracystic bleeding, which was hyperintense in T1W that is not enhanced with contrast. This series shows an occurrence of 21.4 % of non-schwannomatous tumors in 42 cases of lesions restricted to the IAM. Whenever a solely intrameatal enhanced tumor is detected, it is necessary to think about other diagnostic possibilities rather than VS. Therapeutic management may be changed, specially if radiosurgical treatment is considered.