Inferior Cerebellar Artery Loop Research Articles

Management of a challenging dura-embedded anterior inferior cerebellar artery loop during a retrosigmoid hearing-preserving vestibular schwannoma resection: microsurgical technique and operative video. Illustrative case.

Anatomical variants of the anterior inferior cerebellar artery (AICA), such as an anomalous "AICA loop" embedded in the dura and bone of the subarcuate fossa, increase the complexity and risk of vestibular schwannoma resections. Classically, osseous penetrating AICA loops are the most challenging to mobilize, as the dura must be dissected and the surrounding petrous bone must be drilled to mobilize the AICA away from the surgical corridor and out of harm. The authors present a rare case of a dura-embedded, osseous-penetrating AICA loop encountered during a hearing-preserving retrosigmoid approach in which they demonstrate safe and efficient microdissection and mobilization of the AICA loop without having to drill the surrounding bone. Although preoperative recognition of potentially dangerous AICA loops has been challenging, thin-sliced petrous bone computed tomography scanning and high-quality magnetic resonance imaging can be useful in preoperative diagnosis. Furthermore, this report suggests that a retrosigmoid approach is superior, as it allows early intradural recognition and proximal vascular control and facilitates more versatile mobilization of AICA loops.

Neurovascular Conflict Causing Isolated 6th Nerve Palsy

There are many intracranial pathologies of isolated 6th nerve palsy but neurovascular conflicts causing isolated 6th nerve palsy is very rare condition. We present a case of isolated abducens nerve palsy due to neurovascular conflicts caused by indentation and mass effect from left vertebral artery and left anterior inferior cerebellar artery (AICA) loop on the left VI cranial nerve.

Anterior inferior cerebellar artery loop and tinnitus—is there any association between them?

BackgroundWhere there is no identifiable cause of otologic symptoms like hearing loss and tinnitus, it is believed that etiology could possibly involve a vascular loop in AICA compressing the vestibulo-cochlear nerve within the internal auditory canal. In this study, we aim to evaluate whether there is any association of AICA vascular loops with unexplained tinnitus.MethodsThe present prospective study was conducted in the Department of ENT, SMGS Hospital, GMC Jammu, from October 2020 to March 2022 on 131 subjects with unexplained tinnitus. All subjects were subjected to contrast enhanced MRI brain (3D fast spin echo T2W1 with drive equilibrium pulse) for evaluation of AICA using Chavda classification—type 1 (lying in CP angle, but not entering IAC), type 2 (entering IAC but extending < 50% of length of IAC), and type 3 (extending > 50% of length of IAC).ResultsOut of 131 unexplained tinnitus cases, 76 patients (58%) had AICA loop on MRI. Out of 16 patients with right sided tinnitus, 11 patients had AICA on same side, while 5 patients had AICA on the opposite (left) side. Out of 26 patients with left-sided tinnitus, 12 patients had AICA on same side, while 14 patients had AICA on the opposite (right) side, these findings being statistically insignificant (p = 0.153).ConclusionFrom our study, we can conclude that the presence of AICA vascular loop either on CP angle or within IAC in tinnitus patients is an incidental finding and has no role in its etiology.

Etiopathology and Prevalence of Pulsatile Tinnitus in a Tertiary Care Referral Hospital.

The diverse etiopathogenesis of pulsatile tinnitus (PT) makes it a difficult condition to diagnose and treat. To describe the clinical features, investigations and diagnosis of patients presenting with pulsatile tinnitus (PT). Retrospective chart review in an otology unit of a tertiary care referral centre. All medical records of patients who had a complaint of pulsatile tinnitus during the period 1st January 2014-1st May 2020 were included in the study. Data regarding history, characteristics of tinnitus, examination findings, investigations and diagnosis were collected and analyzed. Sixty-four patients with complaints of PT presented to our clinic during this time period and were included in the study giving a prevalence of 0.09%. Definite diagnosis was made in 62 (96.8%) cases with a detailed history, clinical examination and tailored investigations. Pathologies diagnosed were paraganglioma (25%), superior semicircular canal dehiscence (20.3%), anterior inferior cerebellar artery loop (7.8%), sigmoid sinus wall dehiscence (10.9%), sigmoid sinus diverticulum (6.25%), jugular bulb anomalies (7.8%) and hyperpneumatised petrous apex (3.1%) among others. Rare causes encountered were IgG4 disease, far advanced otosclerosis, vestibular aqueduct dehiscence and idiopathic intracranial hypertension. Pulsatile tinnitus is a rare complaint in the Otology clinic. Almost all cases of PT can be diagnosed correctly and appropriate treatment initiated with a logical approach to investigations.

Outcome of Endoscope-Assisted Microvascular Decompression in Patients With Hemifacial Spasm Caused by Severe Indentation of the Brain Stem at the Pontomedullary Sulcus by the Posterior Inferior Cerebellar Artery.

Microvascular decompression (MVD) is the most effective treatment option for hemifacial spasm (HFS). However, deeply located forms of compression would require proper identification to allow for adequate decompression. To describe the usefulness of endoscopic visualization in one of the most challenging compression patterns in HFS, where the posterior inferior cerebellar artery (PICA) loop is severely indenting the brain stem at the proximal root exit zone of facial nerve along the pontomedullary sulcus. Radiological and operative data were checked for all patients in whom severe indentation of the brainstem by PICA at pontomedullary sulcus was recorded and endoscope-assisted MVD was performed. Clinical correlation and outcome were analyzed. A total of 58 patients with HFS were identified with radiological and surgical evidence proving brainstem indentation at the VII transitional zone. In 31 patients, PICA was the offending vessel to the facial nerve. In 3 patients, the PICA loop was mobilized under visualization of a 45° endoscope. A total of 31 patients had a mean follow-up duration of 52.1 mo. The mean duration between start of complaints and surgery was 7.2 yr. In the last follow-up, all patients had remarkable spasm improvement. A total of 5 patients had more than 90% disappearance of spasms and 26 patients experienced spasm-free outcome. Although severe indentation of brain stem implies morphological damage, outcome after MVD is excellent. A 45° endoscope is extremely helpful to identify compression down at the pontomedullary sulcus. Deeply located compression site can easily be missed with microscopic inspection alone.

Hearing Outcomes after Microvascular Decompression for Hemifacial Spasm: An Institutional Experience.

Introduction:Hearing loss following microvascular decompression (MVD) for hemifacial spasm is one of the most dreaded complications. Several factors such as stretching of VIII cranial nerve, vasospasm of labyrinthine artery, and acoustic trauma due to drill noise may be considered in its causation. We evaluated the incidence and severity of hearing loss following MVD in hemifacial spasm and the factors which might be responsible for this complication.Methods:A retrospective analysis of 30 patients operated for hemifacial spasm between January 1, 2014, and December 31, 2018, with at least 3 months of follow-up were included in the study. Retromastoid craniotomy was made, and Teflon was placed between involved vessel and VII nerve.Results:Freedom from hemifacial spasm was noted in 27 of 30 patients. Moderate spasm persisted in one patient, which was controlled with medications. The recurrence was noted in 3 patients at 6 months follow-up. Postoperatively, hearing loss was found in one female patient. The offending vessel was both anterior inferior cerebellar artery (AICA) and posterior inferior cerebellar artery (PICA) loop, which was transpositioned during surgery, and the patient was spasm free postoperatively.Conclusion:The incidence of hearing loss following MVD can be minimized using proper surgical techniques and various intraoperative adjuncts such as brainstem auditory evoked responses monitoring, use of endoscope, and indocyanine green or dual-image video angiography.

Single-sided deafness related to neural vascular conflict: A case report from Saudi Arabia

The impact of single-sided deafness (SSD) is well known, particularly on children. These include difficulties in speech comprehension with background noise, localization, and spatial appreciation. The social and emotional status of the child may be compromised. In addition, parents are keen to understand the etiology and consequences of SSD. Different etiologies are correlated with SSD, and etiology identification is a crucial step toward better management and parent counseling. SSD related to neural vascular conflict (NVC) of the cerebellopontine angle is uncommon. This is the first case, up to my knowledge so far, to be reported in Saudi Arabia. A 13-year-old Saudi girl presented with a history of difficulty in hearing in the left ear, and audiological evaluation demonstrated left-sided profound sensorineural hearing loss. Upon further investigation, magnetic resonance imaging (MRI) showed a left-sided neural vascular conflict of the anterior inferior cerebellar artery (AICA) loop and the left cochlear nerve. In this case, SSD was related to NVC since clinical history, and other investigations did not justify another cause. This report will embrace the role of audiological and radiological investigation, which in turn will help with management recommendations, and help clinicians in dealing with similar challenges.

Is endoscopic inspection necessary to detect residual disease in acoustic neuroma surgery?

To analyze how and when the endoscope is used in vestibular schwannoma surgery and identify the benefits of using endoscopy in this type of surgery. It is currently unclear if there is any benefit from using an endoscope in vestibular schwannoma surgery so this retrospective analysis set out to study this. All the patients who underwent vestibular schwannoma surgery at our clinic were included for all the vestibular schwannoma approaches taken. We studied when endoscopy was used during surgery and the goal of using endoscopy. Several pre- and postoperative factors were assessed such as complications, facial function, and hearing function in the case of techniques that allow hearing preservation. From January 2015 to September 2018, 280 patients underwent lateral skull base surgery. Of these, 112 were included in this study. The endoscope was used in all 112 patients, and in eight cases it was possible to identify residual disease using the endoscope to check the surgical field, and then to remove the disease under endoscopic view. Moreover, in two other cases, the endoscope was used to resolve a vasculoneural conflict between the anterior inferior cerebellar artery (AICA) loop and facial nerve in one case, and for deafferentation of the superior and inferior vestibular nerves in the second case. No major intraoperative complications occurred in our series. There was no statistically significant difference in postoperative facial nerve function between patients in whom the endoscope was used as a diagnostic tool and patients in whom it was used as an operative tool (p = 0.3152). The endoscope may be useful, especially in surgical techniques where there is poor control of the internal auditory canal (IAC). An endoscopic support technique is strongly recommended to avoid residual disease, particularly in retrosigmoid and retrolabyrinthine approaches. Moreover, the recent introduction of the transcanal transpromontorial approach allows the endoscope to be used during all the procedures in patients affected by a vestibular schwannoma limited to the IAC or to support surgical procedures during an enlarged microscopic approach.

Chronic Vestibular Syndrome Associated with Anterior Inferior Cerebellar Artery loop into the Internal Acoustic Meatus (P5.6-033)

Chronic Vestibular Syndrome Associated with Anterior Inferior Cerebellar Artery loop into the Internal Acoustic Meatus (P5.6-033)

Vascular Offenders in Trigeminal Neuralgia: A Unified Classification and Assessment of the Outcome of Microvascular Decompression

Vascular loop compression remains the most accepted theory for trigeminal neuralgia (TN). Apart from the normal adjoining vascular loops, certain unusual vascular loops incriminated in TN such as vertebrobasilar dolichoectasia and pure venous compressions do not truly fit into the traditional classification. Moreover, vascular diseases such as cavernoma and aneurysms causing TN are considered as secondary TNs. There is a lack of unified classification for TN with underlying vascular offenders, otherwise amenable to microvascular decompression. We classified vascular offenders in TN (n= 53) into the usual offenders such as superior cerebellar artery or anterior inferior cerebellar artery loop with (n= 4) or without (n= 34) superior petrosal vein loop (n= 38, group I). The unusual vascular offenders (n= 15, group II) comprised unusual arterial loops (n= 4, IIa), pure venous compressions (n= 8, IIb) and vascular diseases (n= 3, IIc). The clinical symptoms, pain severity scores, and surgical outcomes were compared. A right-sided preference and male predominance typified the unusual group. The incidence of atypical pain and sensory impairment was higher in group II. Group II also showed a less favorable immediate pain outcome, particularly the patients in group IIb. Group IIb also showed a higher incidence of postoperative hemorrhagic complications. However, long-term outcomes did not differ significantly. Unusual vascular offenders in TN do constitute a significant population. They differ from the usual group with respect to the type of pain, gender, and side of involvement and tend to have more complications with similar pain outcomes after microvascular decompression.

Microvascular Decompression and Nervus Intermedius Sectioning for the Treatment of Geniculate Neuralgia.

Objectives Demonstrate the surgical treatment of geniculate neuralgia via microvascular decompression and nervus intermedius sectioning. Designs Single case-based operative video. Setting Tertiary center with dedicated skull base team. Participants The patient is a 62-year-old female with a history of deep right-sided otalgia consistent with geniculate neuralgia. She failed appropriate medical treatment. Her magnetic resonance imaging (MRI) showed an ectatic vertebrobasilar system as well as an anterior inferior cerebellar artery (AICA) loop causing compression of the VII/VIII nerve complex in the cerebellopontine angle. Main Outcome Measures Resolution of right-sided otalgia. Results The patient underwent retrosigmoid craniotomy with microvascular decompression of the VII/VIII nerve complex and nervus intermedius sectioning. Intraoperatively, the patient was noted to have an ectatic vertebral artery and AICA that were compressing the root entry zone of the VII/VIII nerve complex. Microvascular decompression was performed of both the vertebral artery and AICA with Teflon. The nervus intermedius was sharply sectioned. The patient's postoperative course was uneventful with no complications. She continues to have resolution of her right sided otalgia at 6 months postoperatively. The link to the video can be found at: https://youtu.be/uRb_QfrINSk .

THE CAUSE OF SELDOM INCIDENCE OF GLOSSOPHARINGEAL NERVE NEURALGIA

Trigeminal neuralgia (TN) and glossopharyngeal neuralgia (GN) are caused by compression of the roots of these nerves by adjacent vessels – neurovascular conflict. The purpose of the research was to study the topographic and anatomical relationship of the trigeminal nerve root (TNR) with the superior cerebellar artery and the glossopharyngeal nerve root (GNR) with the posterior inferior cerebellar artery, and to assess the impact of anatomical pattern on frequency of glossopharyngeal and trigeminal neuralgia occurring. Topographic and anatomical relationship of glossopharyngeal and trigeminal nerves with adjacent arteries was studied in 50 anatomic specimens (in sito) of persons who did not suffer from trigeminal or glossopharyngeal neuralgia. The specifics of neurovascular conflict in 4 patients with glossopharyngeal neuralgia were also analyzed during microvascular decompression surgery. The superior cerebellar artery loop crossed the surface of the trigeminal nerve root in 44 % of anatomical specimens of subjects without neuralgia during life-time. In a case of age vessel dolichoectasia the peak of the arterial loop would be located below the upper edge of the trigeminal nerve root resulting in the neurovascular conflict. In most anatomical specimens the posterior inferior cerebral artery loop was located collateral to the glossopharyngeal nerve root, preventing development of neurovascular conflict. Only in one of the 50 specimens the artery loop was placed at an angle with the glossopharyngeal nerve. In patients with glossopharyngeal neuralgia microvascular decompression surgery revealed that the distal arm of the posterior inferior cerebellar artery loop was located at an angle with the glossopharyngeal nerve root. Thus, the special topographic and anatomical relationship between the glossopharyngeal nerve and the posterior cerebellar artery cause much rarer occurrence of the glossopharyngeal neuralgia in comparison with the trigeminal neuralgia.

The Association of Anterior Inferior Cerebellar Artery in IAC with Tinnitus and Hearing Loss

Objective: Tinnitus is a common disorder, but the etiology of this disorder remains unknown. The objective of this study was to assess the correlation between anatomic type and the thickness of the anterior inferior cerebellar artery (AICA) loop with tinnitus, using 3D-fast imaging employing steady state acquisition magnetic resonance image (MRI). Method: Seventy-four patients with tinnitus and 82 asymptomatic controls were included in this study. Otologic symptoms, which were measured based on the results of a pure tone audiometry, were reviewed. We evaluated the position and thickness of the AICA vascular loop in 3D-FIESTA MRI using 2 scoring systems. The first system was Chavda classification based on the anatomic location of the AICA loop. The second scoring system was used to measure the thickness of the AICA loop. The AICA loops were classified into 2 groups based on thickness, thinner than adjacent facial nerve and thicker than the facial nerve. Results: Ears with type I, II AICA loops showed significantly higher rates of tinnitus than those with type III. There was no association between the type of AICA loop and subtype of tinnitus (pulsatile, nonpulsatile). There was no association between the type of tinnitus and hearing loss. Ears with thinner AICA loop had a higher rate of tinnitus than those with thicker AICA loop. Conclusion: The type I, II and thinner AICA loop was significantly correlated with tinnitus. Compression of VIIIth cranial nerve by AICA loops at a cerebellopontine angle and impaired blood flow through thevessel may be the pathophysiology of tinnitus.

A Painful Pause

An 83-year-old man had lancinating throat pain, triggered by swallowing, coughing, and even speaking. He would pass out with excruciating pain. Magnetic resonance imaging showed an abnormal posterior inferior cerebellar artery loop (PICA) (left, arrow) exiting the brainstem (left, arrowhead), near the left glossopharyngeal and vagus nerves. Arterial compression from the posterior inferior cerebellar artery on the cranial nerves could produce demyelination, resulting in abnormal cross-conduction. Pain and syncope disappeared with carbamazepine treatment. Severe pain can cause vasovagal syncope,1 but direct vagal stimulation was responsible for asystole in our patient (right). A pacemaker will not prevent syncope if pain is associated with a vasovagal response.2

The Clinical Correlation between Anterior Inferior Cerebellar Artery and Sudden Sensorineural Hearing Loss

Background and Objectives The influence of anterior inferior cerebellar artery (AICA) loop on sudden sensorineural hearing loss (SSHL) remains controversial. The objective of this study was to evaluate the correlation between the anatomical type of AICA loop and SSHL. Subjects and Method We reviewed the medical records of 69 ears from 60 patients with SSHL between January 2005 and April 2008, retrospectively. AICA loops were classified according to the Chavda classification method by magnetic resonance imaging. According to the extension depth of the loop in the internal auditory canal, it was classified as type I, II and III. The loop was classified as S (small diameter) and L (large diameter) by comparing the thickness of the loop with adjacent facial nerves. Results The predominant type of AICA loop was type I (68.1%) and type S (78.3%). There was no significant correlation between the pretreatment hearing level, extension depth and diameter. There was also no significant correlation between the rate of hearing recovery by Siegel's criteria and diameter. However, there was significant correlation between the rate of hearing recovery by Siegel's criteria and the types of the extension depth (p

Paroxysmal otalgia due to compression of the intermediate nerve: a distinct syndrome of neurovascular conflict confirmed by neuroimaging

The authors present the case of a 52-year-old female patient with a 6-year history of intractable paroxysmal otalgia. Preoperative magnetic resonance (MR) angiography demonstrated an anterior inferior cerebellar artery loop compressing the intermediate nerve in the seventh/eighth cranial nerve complex inside the internal auditory canal. The pain resolved completely after a microvascular decompression via a retromastoid craniotomy. To the best of the authors' knowledge, the combined neuroimaging and intraoperative findings of this case provide a unique demonstration that vascular compression of the intermediate nerve can be the exclusive cause of paroxysmal otalgia. Magnetic resonance imaging and MR angiography can establish the causative mechanism and distinguish this otalgia due to vascular compression of the intermediate nerve from other pain syndromes that are designated as geniculate neuralgia (GN). The present case indicates that intermediate nerve neuralgia is a distinct syndrome of neurovascular conflict and a variant of GN. The causative classification of GN should be reexamined with the use of advanced MR imaging.

Paroxysmal otalgia due to compression of the intermediate nerve: a distinct syndrome of neurovascular conflict confirmed by neuroimaging

✓The authors present the case of a 52-year-old female patient with a 6-year history of intractable paroxysmal otalgia. Preoperative magnetic resonance (MR) angiography demonstrated an anterior inferior cerebellar artery loop compressing the intermediate nerve in the seventh/eighth cranial nerve complex inside the internal auditory canal. The pain resolved completely after a microvascular decompression via a retromastoid craniotomy. To the best of the authors' knowledge, the combined neuroimaging and intraoperative findings of this case provide a unique demonstration that vascular compression of the intermediate nerve can be the exclusive cause of paroxysmal otalgia. Magnetic resonance imaging and MR angiography can establish the causative mechanism and distinguish this otalgia due to vascular compression of the intermediate nerve from other pain syndromes that are designated as geniculate neuralgia (GN). The present case indicates that intermediate nerve neuralgia is a distinct syndrome of neurovascular conflict and a variant of GN. The causative classification of GN should be reexamined with the use of advanced MR imaging.

Is Microvascular Compression of the Vestibulocochlear Nerve a Cause of Unilateral Hearing Loss?

We sought to confirm earlier findings in the literature that microvascular compression of the vestibulocochlear nerve might cause unilateral sensorineural hearing loss. We measured the length and width of the internal auditory canal (IAC) to investigate a possible association between a narrow porus, the presence of an anterior inferior cerebellar artery (AICA) loop, and the development of a microvascular compression syndrome. We performed a prospective blinded analysis of 167 magnetic resonance imaging scans of the cerebellopontine angle. The presence of an AICA loop was scored. We analyzed these 167 patients for unilateral sensorineural hearing loss, which was defined as an interaural difference of 20 dB at 1 frequency or 10 dB at 2 or more frequencies. Furthermore, the width and length of the IAC on magnetic resonance imaging were measured. An AICA loop was identified in 94% of the 167 patients. There were 196 type I loops, 106 type II loops, and 14 type III loops. Sixty-six patients had unexplained unilateral hearing loss. There was no association between type II and III vascular loops, the width of the IAC, and unilateral hearing loss (p > .05). In this study we found no association between the depth of extension of the AICA loop into the IAC and the presence of unilateral hearing loss.

Cerebellopontine Angle Epidermoid Tumor Presenting With 'Tic Convulsif' and Tinnitus. Case Report.

A 22-year-old female presented with a cerebellopontine angle epidermoid tumor manifesting as a rare combination of hemifacial spasm, trigeminal neuralgia, and tinnitus. Magnetic resonance imaging demonstrated the tumor distorting the brainstem and the fourth ventricle. The tumor was almost completely resected and the seventh-eighth cranial nerve complex was decompressed by mobilizing the anterior inferior cerebellar artery loop. No arterial loop was related to the trigeminal nerve. The patient was completely relieved of the "tic convulsif" and tinnitus after the surgery. The inflammatory nature of epidermoid tumor may be involved in the etiology of the syndrome. Microvascular decompression may be needed in addition to tumor removal in such cases.

The anterior inferior cerebellar artery in the internal auditory canal

It has been proposed that compression of the auditory and vestibular nerve trunks by vascular loops might be the cause of otherwise unexplained hearing loss, tinnitus, and vertigo, as well as Meniere's disease. We studied the human temporal bone histological collection at the Massachusetts Eye and Ear Infirmary to determine whether audiovestibular symptoms could be correlated with the presence of the anterior inferior cerebellar artery within the internal auditory canal. Anterior inferior cerebellar artery loops were found within the internal auditory canals of 12.3% of 1327 temporal bones, about half the number found when preparations with intact brains are studied. This difference can be attributed to avulsion of the anterior inferior cerebellar artery during removal of the brain at autopsy. There were 5 cases of unexplained unilateral hearing loss with anterior inferior cerebellar artery loops: 3 in the opposite ear and 2 in both ears. There were 2 cases with unilateral unexplained tinnitus with anterior inferior cerebellar artery loops: 1 in the involved ear and 1 in the opposite ear. A case with bilateral tinnitus had an anterior inferior cerebellar artery loop in 1 ear. There were 29 cases of vertigo with no peripheral histopathological correlate or central nervous system disorder; anterior inferior cerebellar artery loops were found in the internal auditory canals of 7 (12.5%) of the 56 ears in this group, which is not significantly different from the 12.3% incidence recorded for the entire collection. In 23 cases of unilateral Meniere's disease, there were anterior inferior cerebellar artery loops in the hydropic ears in 3, the opposite ear in 1, and both ears in 1. We can find no correlation between unexplained hearing loss, tinnitus, vertigo, or Meniere's disease and the presence of the anterior inferior cerebellar artery in the internal auditory canal.