Evaluation of the Relationship Between the Internal Acoustic Canal Anatomy and Loops of the Anterior Inferior Cerebellar Artery Using 3-Tesla Magnetic Resonance Imaging

Background: Anatomical variations in vascular structures are frequently encountered. In the cerebellopontine region, anatomical variations, especially variations in the anterior inferior cerebellar artery (AICA) in relation to cranial nerves passing through the internal acoustic canal (IAC), are common. Magnetic resonance imaging (MRI) provides detailed information for the evaluation of the cerebellopontine region and the IAC anatomy. Objectives: This study aimed to examine the relationship between the IAC anatomy and AICA loop variations and to investigate the frequency of anatomical variations and its correlation with demographic variables. Patients and Methods: In this study, 253 patients (age > 18 years), who underwent 3-Tesla MRI of the temporal bone between July 2019 and December 2019, were retrospectively evaluated. The exclusion criteria were images of poor diagnostic quality due to technical or patient-related reasons and the presence of a localized tumor that could disrupt the IAC. Four patients were excluded from the study because they had tumors related to IAC. The AICA variations were categorized according to the Chavda classification. The IAC size, canal diameter, canal length, and meatus width were measured, and the canals were characterized as cylindrical, funnel-shaped, and bud-shaped. Results: A total of 249 patients were included in this study. The Chavda type I vascular loop was the most common type on both sides. The mean size measurements of IACs were significantly higher in the group of vascular loops compared to the group without vascular loops. The presence of a vascular loop was significantly more common in funnel- and bud-shaped IACs compared to cylindrical IAC. Also, there was a negative correlation between the patient’s age and all IAC dimensions. Conclusion: The results of the present study showed that the AICA loop variations were closely related to the size and shape of the IAC.

Bilateral Nervus Intermedius Sectioning for Geniculate Neuralgia: Case Report and Operative Video

BACKGROUND AND IMPORTANCE Geniculate neuralgia is a rare condition characterized by excruciating ear pain. Surgical options for geniculate neuralgia include microvascular decompression and sectioning of the nervus intermedius. We report herein a case of bilateral geniculate neuralgia treated by nervus intermedius sectioning without prior microvascular decompression. To our knowledge, this is the first report of this treatment strategy with a subsequent description of the side effects of bilateral nervus intermedius disruption. CLINICAL PRESENTATION A 54-yr-old woman presented with bilateral geniculate neuralgia, worse on the left, refractory to medical therapy. Surgical treatment options were reviewed, including microvascular decompression and sectioning of the nervus intermedius. She opted for left nervus intermedius sectioning. The procedure was uncomplicated and no compressive vascular loop was identified during surgery. Postoperatively, she had complete symptom resolution with no discernable side effects. Three years later, the patient developed worsening geniculate neuralgia on the contralateral side. After the discussion of treatment options, she opted again for sectioning of the contralateral nervus intermedius with successful resolution of all symptoms after surgery. Following surgery, the patient identified partial impairment of lacrimation and gustation. She continued to have functional taste of the anterior two-thirds of the tongue, lacrimation, and hearing bilaterally. CONCLUSION Bilateral sectioning of nervus intermedius may provide benefit in patients with bilateral geniculate neuralgia without egregious side effects. However, lacrimatory and gustatory alterations are a potentially significant side effect with a wide range of symptomatology.

Sudden Sensorineural Hearing Loss Associated with the Presence of a Vascular Loop in the Internal Auditory Canal. Case Report

The vascular loop refers to a trajectory abnormality of the antero-inferior cerebellar artery or its branch in the internal auditory canal. The Chavda radiological classification identifies three types of trajectory depending on the depth of penetration of the loop at the level of the internal auditory canal. The article presents the case of a 26-year-old patient admitted to the ENT department for left ear sudden sensorineural hearing loss and dizziness. The 3D Fiesta-C axial sequence MRI shows the presence of the vascular loop inside the internal auditory canal, without exceeding half of it. The hearing loss had an unfavourable evolution, without recovery after treatment with steroids and vasodilators. Sudden sensorineural hearing loss may be a consequence of the presence of the vascular loop in the internal auditory canal. The prognosis for recovery from hearing loss is poor if the loop is at least type II.

Vascular Loops: The Innocent Bystander for Vestibular Paroxysmia

Introduction: Vestibular paroxysmia (VP) is a condition with recurrent short bouts of vertigo and is thought to be part of a neurovascular compression syndrome caused by the vascular loop. However, this is still being debated as vascular loops are considered as normal variants with limited studies involving vertiginous patients. Objectives: The aim of this paper is to study the association between audiovestibular symptoms and the presence of vascular loops and to study the association between vestibular paroxysmia and vascular loops. Design: This is a retrospective analysis of clinical, audiological and MRI findings of patients with and without vascular loops and vestibular paroxysmia from 2000 to 2020. Results: A total of 470 MRI Internal Auditory Meatus scans were performed during the study period of which, 71 (15.1%) had vascular loops and 162 (34.5%) had normal MRI which were used as controls. From the 233 subjects recruited, there were 37 subjects with VP and 196 non VP subjects were used as controls. There was no association between the vascular loop and control groups in terms of co-morbidity and audiovestibular symptoms. The VP group had a significantly older mean age of 51.8 (SD ± 10.3) as compared to the non VP group with the mean age of 45.6 (SD ± 15.5). The VP group had higher number of patients presenting with hearing loss at 97.3% when compared with those without VP (80.1%) ( P = .01). The odds of having a vascular loop giving rise to VP was not statistically significant at 0.82 (95% CI 0.3735-1.7989) P = .62. Conclusion: The vascular loop is a normal variant which may or may not give rise to audiovestibular symptoms or vestibular paroxysmia. Clinical assessment is still most important tool in deriving a diagnosis of VP and MRI may be useful to rule out other central causes.

Trigeminal neuralgia secondary to onyx embolization of a right occipital arteriovenous malformation

Background: Trigeminal neuralgia is a debilitating chronic condition characterized by severe recurrent hemifacial pain which is often caused by compression of the trigeminal nerve by an adjacent vessel loop. Microvascular decompression (MVD) surgery is an effective procedure that can lead to full symptomatic relief. Intracranial arteriovenous malformations (AVMs) are primarily congenital abnormalities that may be asymptomatic or manifest as seizures or focal neurologic deficits. They may cause intracranial bleeding and hence are promptly treated, often by endovascular embolization. This procedure is safe but may have a multitude of unpredictable complications. Case Description: A 33-year-old female presented with medically refractory trigeminal neuralgia secondary to Onyx embolization of a right occipital AVM 3 years prior. She underwent surgical exploration and MVD of the trigeminal nerve root which was found to be compressed by the previously embolized superior cerebellar artery. The procedure was successful and full symptomatic resolution was immediately achieved. Conclusion: Postprocedural trigeminal neuralgia is a procedural complication of Onyx endovascular embolization. It may be treated by MVD surgery regardless of the presence or absence of a compressive vascular loop on imaging.