Secondary Trigeminal Neuralgia Caused by Cerebellopontine Angle Arachnoid Cyst in A 27-Year-Old Female: A Case Report

PURPOSE

Secondary (TN) caused by an arachnoid cyst in the (CPA) region is a rare finding. Based on the reported literature, there are only 5 cases of secondary trigeminal neuralgia caused by an arachnoid cyst in the cerebellopontine angle region.

CASE REPORT

A 27-year-old female presented to our neurosurgery clinic with a 2-year history of brief episodes of paroxysm pain in the left cheek. The pain was described as an electric shock-like pain triggered by simple stimuli. The magnetic resonance imaging (MRI) showed a well-confined cystic lesion in the left CPA, which compresses the left pons and the cisternal segment of the left trigeminal nerve. The patient was managed operatively to fenestrate the cyst and decompress the trigeminal nerve. The histopathological result of the cyst wall was consistent with an arachnoid cyst. Six months after surgery, the patient is in good health condition and symptom-free without medication.

CONCLUSION

Arachnoid cyst in the CPA region is one of the rare causes of secondary TN. Preoperative imaging with MRI is important to provide better results to differentiate the pathology. Surgical treatment to fenestrate the arachnoid cyst and decompress the trigeminal nerve have a good result and can improve the patient's quality of life.

Arachnoid Cyst of the Cerebellopontine Angle: A Systematic Literature Review

OBJECTIVE

The role of surgical management of arachnoid cyst (AC) of the cerebellopontine angle (CPA) is uncertain. This topic has remained controversial with varying contradictory recommendations in the literature, which is limited to mostly case reports. We aimed to provide a comprehensive summary and analysis of symptoms, operative techniques, outcomes, and recurrence of all available surgical cases of AC of the CPA to date.

METHODS

A systematic literature search was performed in May 2022 querying several scientific databases. Inclusion criteria specified all studies and case reports of patients with AC located at the CPA for which any relevant surgical procedures were performed.

RESULTS

A total of 55 patients from the literature and 5 treated at our institution were included. Mean patient age was 29 years (range, 0.08-79 years), with nearly twice (1.7×) as many female as male patients (37 female, 22 male). Headaches (35%), hearing loss (30%), vertigo (22%), and ataxia (22%) were the most common presentations. Following surgery, 95% experienced symptom improvement, with complete resolution in 64%. Of patients with hearing loss, 44% reported a return to normal. The rate of mortality was 1.69%, and 10% of tumors recurred (mean follow-up 2.3 years [range, 0-15 years].

CONCLUSIONS

Symptomatic AC of the CPA is rare. It exhibits a proclivity for females and commonly manifests with headache, hearing loss, vertigo, and ataxia. While careful selection for surgical candidacy is needed and intervention should be reserved for patients with severe symptoms, surgical decompression is an effective tool for symptom alleviation and recovery.

Cerebellopontine angle tumor presenting as acute audiovestibular syndrome

BACKGROUND

Acute audiovestibular deficits may be a harbinger of vestibular schwannoma (VS).

OBJECTIVE

To investigate clinical and laboratory features of 25 consecutive patients with VS presenting with acute audiovestibular deficits.

METHODS

A symptomatic combination of acute audiovestibular deficits was investigated. Audiometric and vestibular function tests, and internal auditory canal magnetic resonance imaging (IAC MRI) results were evaluated.

RESULTS

Varying combinations of symptoms may develop in VS patients with acute audiovestibular deficits, of whom sudden hearing loss (HL) without acute vertigo or acute facial nerve palsy (FNP) was most common. The most common audiometric configuration was high-tone hearing loss, and no patient showed low-tone hearing loss. IAC MRI demonstrated that the tumor had an intracanalicular portion and attachment to the bony IAC wall in all patients and widened the IAC wall in some patients.

CONCLUSION

Different symptomatic combinations of acute audiovestibular deficits may develop in patients with VS. Awareness about the possibility of VS as a cause of sudden HL, acute vertigo, and acute FNP, as well as subsequent IAC MRI scanning is vital to earlier diagnosis of VS in these patients.

Balloon compression, neuroendoscopy and electrophysiological monitoring-assisted retrosigmoid approach for resection of cholesteatoma in the cerebellopontine angle-Meckel's cave: a technical description

We report a case of cholesteatoma that caused left facial pain with facial numbness. The tumour was located in the left cerebellopontine angle (CPA) and Meckel's cave. A balloon was first placed into Meckel's cave, and then, under electrophysiological monitoring, the tumour within the CPA cistern was resected via the retrosigmoid approach. The balloon was inflated in Meckel's cave to push the tumour out of Meckel's cave, and then, the tumour was completely removed under endoscopy. The symptoms, including pain and numbness, subsided after surgery.

The cerebellopontine angle cistern volumetric differences in trigeminal neuralgia patients with and without vertebrobasilar compression: a case-matched study

Previous studies have indicated that the small cerebellopontine angle (CPA) cistern plays a role in the pathogenesis of trigeminal neuralgia (TN), but they are likely not involved in TN associated with vertebrobasilar artery (VBA) compression because of its rarity. Forty-four patients with VBA-associated TN and 44 age-, sex-, and hypertension-matched TN patients without VBA compression (non-VBA-associated) were included. All patients underwent high-resolution MRI. The CPA cistern volumes were measured bilaterally. The presence of vertebrobasilar dolichoectasia (VBD) and laterality of the vertebrobasilar junction (VBJ) were observed. The CPA cistern volume on the affected side was smaller than the unaffected side (714.4 ± 372.8 vs 890.2 ± 462.2 mm3, p < 0.001) in non-VBA-associated TN patients, while VBA-associated TN patients show a larger CPA cistern on the affected side than the unffected side (1107.0 ± 500.5 vs 845.3 ± 314.8 mm3, p < 0.001). The prevalence of VBD was higher in patients with VBA-associated TN than in matched non-VBA-associated TN patients (90.9% vs 4.5%, p < 0.001). A positive correlation between the laterality of VBJ and the affected side was found in the VBA-associated TN group (p < 0.0001). Large CPA cistern may be a neuroradiological feature of VBA-associated TN, and most of the VBA-associated TN is accompanied by VBD. The presence of VBD and the lateral shift of VBJ may expand the CPA cistern by squeezing the surrounding tissue on the affected side and also increase the chance of VBA compression on the trigeminal nerve, resulting in the genesis of VBA-associated TN.

Bruns Nystagmus in Cerebellopontine Angle Hemangioblastoma

Bruns nystagmus is a form of jerk nystagmus that has a localizing value in cerebellopontine angle (CPA) tumors. Hemangioblastomas involving the CPA is rare. A case of a 57-year-old male presented with Bruns nystagmus which led to the discovery of a large CPA hemangioblastoma is described. The nystagmus was compatible with the laterality of the tumor. High quality video of Bruns nystagmus was recorded.

Upfront Radiosurgery vs a Wait-and-Scan Approach for Small- or Medium-Sized Vestibular Schwannoma: The V-REX Randomized Clinical Trial

Importance

Current guidelines for treating small- to medium-sized vestibular schwannoma recommend either upfront radiosurgery or waiting to treat until tumor growth has been detected radiographically.

Objective

To determine whether upfront radiosurgery provides superior tumor volume reduction to a wait-and-scan approach for small- to medium-sized vestibular schwannoma.

Design, Setting, and Participants

Randomized clinical trial of 100 patients with a newly diagnosed (<6 months) unilateral vestibular schwannoma and a maximal tumor diameter of less than 2 cm in the cerebellopontine angle as measured on magnetic resonance imaging. Participants were enrolled at the Norwegian National Unit for Vestibular Schwannoma from October 28, 2014, through October 3, 2017; 4-year follow-up ended on October 20, 2021.

Interventions

Participants were randomized to receive either upfront radiosurgery (n = 50) or to undergo a wait-and-scan protocol, for which treatment was given only upon radiographically documented tumor growth (n = 50). Participants underwent 5 annual study visits consisting of clinical assessment, radiological examination, audiovestibular tests, and questionnaires.

Main Outcomes and Measures

The primary outcome was the ratio between tumor volume at the trial end at 4 years and baseline (V4:V0). There were 26 prespecified secondary outcomes, including patient-reported symptoms, clinical examinations, audiovestibular tests, and quality-of-life outcomes. Safety outcomes were the risk of salvage microsurgery and radiation-associated complications.

Results

Of the 100 randomized patients, 98 completed the trial and were included in the primary analysis (mean age, 54 years; 42% female). In the upfront radiosurgery group, 1 participant (2%) received repeated radiosurgery upon tumor growth, 2 (4%) needed salvage microsurgery, and 45 (94%) had no additional treatment. In the wait-and-scan group, 21 patients (42%) received radiosurgery upon tumor growth, 1 (2%) underwent salvage microsurgery, and 28 (56%) remained untreated. For the primary outcome of the ratio of tumor volume at the trial end to baseline, the geometric mean V4:V0 was 0.87 (95% CI, 0.66-1.15) in the upfront radiosurgery group and 1.51 (95% CI, 1.23-1.84) in the wait-and-scan group, showing a significantly greater tumor volume reduction in patients treated with upfront radiosurgery (wait-and-scan to upfront radiosurgery ratio, 1.73; 95% CI, 1.23-2.44; P = .002). Of 26 secondary outcomes, 25 showed no significant difference. No radiation-associated complications were observed.

Conclusion and relevance

Among patients with newly diagnosed small- and medium-sized vestibular schwannoma, upfront radiosurgery demonstrated a significantly greater tumor volume reduction at 4 years than a wait-and-scan approach with treatment upon tumor growth. These findings may help inform treatment decisions for patients with vestibular schwannoma, and further investigation of long-term clinical outcomes is needed.

Trial Registration

ClinicalTrials.gov Identifier: NCT02249572.

Analysis of Imaging Results for Semisitting Compared with Supine Positioning in the Retrosigmoid Approach for Resection of Cerebellopontine Angle Vestibular Schwannomas

OBJECTIVE

To compare the completeness of resection of vestibular schwannomas using three-dimensional segmented volumetric analysis of pre- and postoperative magnetic resonance imaging (MRI) of patients undergoing supine and semisitting positioning for the retrosigmoid approach.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary medical center.

PATIENTS

Patients with vestibular schwannomas undergoing surgical resection via the retrosigmoid approach.

INTERVENTIONS

Tumor resection via the retrosigmoid approach with different patient positioning: standard supine versus semisitting.

MAIN OUTCOME MEASURES

Preoperative versus postoperative three-dimensional segmented volumetric MRI analysis of vestibular schwannomas.

RESULTS

A total of 43 patients (15 supine and 28 semisitting) underwent retrosigmoid craniotomy for resection of vestibular schwannomas. For the conventional supine and semisitting positioning, mean preoperative tumor volumes were 12.65 and 8.73 cm 3 ( p = 0.15), respectively. Postoperative mean tumor volumes for the supine and semisitting positions were 2.09 and 0.48 cm 3 ( p = 0.13), respectively. There were 11 cases of postoperative sigmoid sinus thrombosis, 3 in the conventional supine group and 8 in the semisitting groups, and there were 6 cases of postoperative cerebrospinal fluid leaks, all in the semisitting group. The mean House-Brackmann scores for the supine and semisitting groups were 2.9 and 2.3, respectively. There was no statistically significant difference between groups in the rates of these or any other postoperative complications.

CONCLUSIONS

The semisitting position for the suboccipital retrosigmoid approach for vestibular schwannoma resection does not compromise the ability to adequately resect the tumor as seen by volumetric MRI results. Further studies are needed to establish the safety of this position compared with the traditional supine approach.

Microstructure and Reasonable Management of the Arachnoid Associated with the Infrafloccular Approach for Microvascular Decompression of the Facial Nerve

AIM

To understand the arachnoid microstructure during infrafloccular approach for facial nerve microvascular decompression (MVD).

MATERIAL AND METHODS

This study recruited 55 patients with hemifacial spasm who underwent MVD. Retrospective analyses of the MVD surgical videos were performed to reveal the arachnoid microstructure during the procedures. Cadaveric head specimens (n=8, on 16 sides) were dissected for observation of the microstructure of the arachnoid in the cerebellopontine angle.

RESULTS

The arachnoid membrane surrounding the facio-cochleovestibular and lower cranial nerves forms two arachnoid sheaths. Both arachnoid sheaths contain two parts: the outer membranous and inner trabecular part. The membranous part is an intact and translucent membrane that wraps around nerves. The inner trabecular part is located beneath the membranous part and forms a trabecular network that connects the membranous arachnoid, nerves, and blood vessels to form a physical structure.

CONCLUSION

The arachnoid connects the facio-cochleovestibular and lower cranial nerves, blood vessels, and cerebellum as a complex physical entity. Therefore, during MVD surgery, sharply dissecting the arachnoid before retracting the flocculus and relocating the offending vessels helps reduce nerve injury.

Unusual imaging characteristics of cystic meningioma in cerebellopontine angle

We report a case of cystic meningioma at the left cerebellopontine angle (CPA). Magnetic resonance imaging demonstrated both solid and cystic components in the tumor. The cystic component appeared slightly hyperintense compared to cerebrospinal fluid on fluid-attenuated inversion recovery (FLAIR) imaging. A hypointense tubular structure was identified in the cystic component on 3D driven equilibrium sequencing. These imaging findings are unusual for cystic meningioma. However, awareness of these unusual imaging features is important to determine appropriate treatment strategies although cystic meningioma at the CPA is extremely rare.

Diagnostic performance of quantitative signal intensity measurements on magnetic resonance imaging for distinguishing cerebellopontine angle meningioma from acoustic schwannoma

OBJECTIVE

Our study investigated magnetic resonance imaging measurements for differentiating cerebellopontine angle (CPA) meningioma from vestibular schwannoma (VS).

PATIENTS AND METHODS

This retrospective study compared 36 meningioma and 36 VS patients. The tumor volume (Vtumor) and peritumor edema index (EI) relationship was analyzed. T2-weighted three-dimensional gradient-echo image signal intensity (T23D) and apparent diffusion coefficient (ADC) differentiation cutoff values were defined. Mann-Whitney U test, independent-samples t-test, receiver operating characteristic curve, and Spearman's correlation analyses were applied.

RESULTS

Meningioma had higher Vtumor (p=0.009) and EI (p=0.031) values than VS. Meningioma had significantly (p<0.001) lower values than VS for mean ADC (ADCmean: 0.841±0.083×10-3 vs.1.173±0.190×10-3 mm2/s), minimum ADC (ADCmin: 0.716±0.078×10-3 vs.1.045±0.178×10-3 mm2/s), tumor:white matter ADC ratio (rADC: 1.198±0.19 vs. 1.59±0.30), mean T23D (T23Dmean: 142.91±19.9 vs. 218.72±84.73), and tumor:adipose T23D ratio (rT23d: 0.19±0.06 vs. 0.30±0.28) Cutoff, sensitivity (Se), and specificity (Sp) values were ADCmin, 0.856×10-3 mm2/s (Se: 96.6%, Sp: 100%); ADCmean, 0.963×10-3 mm2/s (Se: 96.6%, Sp: 95.5%); rADC, 1.3189 (Se: 93.1%, Sp: 81.8%), T23Dmean (Se: 96.6%, Sp: 100%); rT23D, 0.1951 (Se: 89.7%, Sp: 100%), Vtumor, 14828.65 mm3 (Se: 75.0%, Sp: 66.7%), and EI, 1.1025 (Se: 47.2%, Sp: 100%).

CONCLUSIONS

ADCmin, ADCmean, rADC, T23Dmean, rT23D, Vtumor, and EI, effectively discriminated meningioma from VS.

Quantitative Chemical Exchange Saturation Transfer Imaging of Amide Proton Transfer Differentiates between Cerebellopontine Angle Schwannoma and Meningioma: Preliminary Results

Vestibular schwannomas are the most common tumor at the common cerebellopontine angle, followed by meningiomas. Differentiation of these tumors is critical because of the different surgical approaches required for treatment. Recent studies have demonstrated the utility of amide proton transfer (APT)-chemical exchange saturation transfer (CEST) imaging in evaluating malignant brain tumors. However, APT imaging has not been applied in benign tumors. Here, we explored the potential of APT in differentiating between schwannomas and meningiomas at the cerebellopontine angle. We retrospectively evaluated nine patients with schwannoma and nine patients with meningioma who underwent APT-CEST MRI from November 2020 to April 2022 pre-operation. All 18 tumors were histologically diagnosed. There was a significant difference in magnetization transfer ratio asymmetry (MTR_asym) values (0.033 ± 0.012 vs. 0.021 ± 0.004; p = 0.007) between the schwannoma and meningioma groups. Receiver operative curve analysis showed that MTR_asym values clearly differentiated between the schwannoma and meningioma groups. At an MTR_asym value threshold of 0.024, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive values for MTR_asym were 88.9%, 77.8%, 80.0%, and 87.5%, respectively. Our results demonstrated the ability of MTR_asym values on APT-CEST imaging to discriminate patients with schwannomas from patients with meningiomas.

Unilateral glossodynia as a harbinger of an occult cerebellopontine angle tumour

A woman in her late 80s with severe bronchomalacia was referred to a tertiary orofacial pain clinic for unexplained right unilateral glossodynia of progressive and continuous evolution for the past 8 months, spreading to the ipsilateral labiomental region, associated with ipsilateral hypoacusia. Local and general clinical examinations were unremarkable and routine blood work could not reveal any underlying systemic disease explaining the glossodynia and burning/pricking labiomental pain. Suspecting a painful trigeminal neuropathy secondary to a space-occupying lesion, a cerebral MRI was prescribed, revealing an ipsilateral cerebellopontine angle lesion, compatible with either a schwannoma or meningioma. This lesion invaded the root entry zones of cranial nerves V and VIII explaining the patient's oral pain and hypoacusia. Following a neurosurgical consultation where surgical treatment was rejected, her pain was successfully managed by topical pregabalin mouthwashes, to prevent any risk of respiratory depression related to her underlying severe bronchomalacia.

Dysfunctions and anatomical relationships of cranial nerves in epidermoids of the cerebellopontine angle

OBJECTIVE

To evaluate the correlation of neurological symptoms with anatomical relationships of cranial nerves, lesions and vessels in patients with epidermoids of the cerebellopontine angle.

MATERIAL AND METHODS

We analyzed neurological symptoms, magnetic resonance data, intraoperative findings and postoperative functional outcomes in 25 patients (14 females and 11 males aged 22-77 years) with epidermoids of the cerebellopontine angle.

RESULTS

Cranial nerve dysfunctions were noted in 15 patients. Involvement of cochlear (n=9) and trigeminal (9 cases including 4 ones with sensory impairment and 5 patients with neuralgia) nerves was the most common. There were 10 patients with ataxia, hemiparesis and seizures without cranial nerve dysfunction. In 15 patients, epidermoids spread to supratentorial space and contralateral cerebellopontine angle. Lesion-induced brainstem compression was found in 22 cases. Cranial nerves and cerebellar arteries were partially or completely enclosed by lesion in all cases. Severe compression and dislocation of the nerve root entry/exit zone were found in all cases. One patient with trigeminal neuralgia had vascular compression of trigeminal nerve caused by superior cerebellar artery. Total resection was achieved in 16 patients. Small capsule remnants were left on vessels, nerves or brainstem in 9 patients. Postoperative complete or partial restoration of cranial nerve functions was noted in 11 cases. Deterioration of preoperative neurological deficit in 4 patients and postoperative neurological symptoms de novo in 3 patients were temporary.

CONCLUSION

Cranial nerve dysfunctions are caused by compression of the nerve root entry/exit zones by epidermoids of the cerebellopontine angle. Surgical intervention is effective in alleviating symptoms of cranial neuropathy and brainstem compression. Vascular decompression should be performed in patients with trigeminal neuralgia.

Hydatid Cyst of the Cerebellopontine Angle

Hydatid disease is caused by Echinococcus granulosus. The liver is the first organ of entry, while the central nervous system is affected in about 2% of cases. Primary brain hydatid cyst is extremely rare. The cysts are generally located in cerebral lobes. Here, we reported a 68-year-old Syrian immigrant woman with hydatid cyst in the left cerebellopontine angle. The patient presented gait disturbance, asymmetrical palatal arcs, negative gag reflex, and disturbed cerebellar tests on the left side. The patient was operated via suboccipital craniotomy. The cyst ruptured during manipulation, but it was totally removed.

Evaluation of Bell's palsy in the cerebellopontine angle: An MRI study

BACKGROUND

Evaluation of cranial nerve morphology through measuring cross-sectional area (CSA) on magnetic resonance imaging (MRI) is increasing day-by-day in clinical diseases. In Bell's palsy (BP), the manifestation of the enlarged CSA of the facial nerve (FN) may be used for diagnosis. This study aims to evaluate whether there is an enlargement of the cisternal FN in BP.

METHODS

This retrospective study included 43 patients diagnosed with BP. In the reconstructed MRI, the long (LD) and short (SD) diameters of the paralytic and normal sides of the FNs located in the cerebellopontine angle were measured, and the CSA was calculated using the Radinsky formula. Before the radiologic measurement, a preliminary experiment was carried out on the rat sciatic nerve to be able to determine the actual nerve boundary on MRI.

FINDINGS

There was a statistically significant relationship between paralytic and normal sides in the measurements of LD, SD, and CSA. The paralytic side was larger than the normal side in the cisternal FN. According to the Receiver Operating Characteristic (ROC) curve, BP can be estimated with 60% sensitivity and 70% specificity by the CSA of the FN more than 1.04 mm² . As a result of the preliminary experiment, it was found that the actual nerve boundary was at approximately 50% intensity between the minimum and maximum values.

CONCLUSION

Although entrapment of FN in the labyrinthine segment in BP was known, this study showed that the cisternal FN, which could be evaluated more conveniently, enlarged in the paralytic side compared with the normal side, and revealed the necessity of performing the comparison amongst the MRI studies on BP patients by a standardised measurement method. This study will also help clinicians to make a decision in the diagnosis of BP by giving a cut-off value for the CSA.

[Trigeminal nerve lipoma presenting with trigeminal neuralgia: case report and literature review]

Cerebellopontine angle lipomas are benign mass lesions and rarely result trigeminal neuralgia. A 61-year-old male with right-sided trigeminal neuralgia in V2 and V3 divisions without sensory disturbances is reported in the article. MRI revealed mass lesion 11´11´4 mm on the lateral pontine surface spreading to the right trigeminal nerve root entry zone. No signs of neurovascular compression were found. Microsurgical exploration of the cerebellopontine angle showed a fatty mass adherent to the brainstem with incorporation of inferior part of trigeminal nerve root. Fatty tissue resection was followed by partial sensory trigeminal rhizotomy. Histological examination identified lipoma. Postoperative MRI showed small residual tissue with minimal ischemic area near trigeminal nerve root entry zone. Mild hypoesthesia within V2 and V3 trigeminal branches occurred after surgery. Trigeminal neuralgia completely resolved, and medications were discontinued. This clinical case and literature review clearly demonstrated successful elimination of trigeminal neuralgia in patients with cerebellopontine angle lipoma after resection of mass lesion and partial trigeminal rhizotomy.

Multi-syphilitic gummas in pituitary and cerebellopontine angle in a patient

PURPOSE

Multi-syphilitic gummas in pituitary and cerebellopontine angle (CPA) are extremely rare and easily misdiagnosed especially in patients with antibiotic abuse. We write this paper for clinicians to better understanding of cerebral gumma.

METHODS

We report a patient with syphilitic gummas in pituitary and left CPA. The definite diagnosis is made by histopathology after surgery.

RESULTS

A 49-years-old woman suffered from headaches with tinnitus and hypoacusis in left ear. She was diagnosed with syphilis but untreated. There were no chancre and rashes in the course of disease. Syphilis serological tests were positive. Brain MRI found two masses located in the left CPA and hypophysial fossa. The two masses were removed successively. We found a large number of Treponemapallidum in paraffin-embedded specimens by immunohistochemical staining.

CONCLUSIONS

Syphilitic gummas in pituitary and CPA are similar to benign or malignant brain tumors, easily leading to misdiagnosis. Gumma should be considered in differential diagnosis when a patient has unexplained nervous system symptoms or signs and imaging findings suggest intracranial mass in syphilis seropositive patients.

Vestibular Impairment in Hemifacial Spasm Syndrome: A Case Report

A 52-year-old man presented with left hemifacial spasm (HFS). A magnetic resonance imaging scan showed compression of the left facial nerve at the cerebellopontine angle by a dolichoectatic basilar artery. The neurotological evaluation showed an otolithic deficit, with canalicular preservation and normal hearing. The deficit improved after surgical decompression. No previous report has described the impairment of vestibular function in patients presenting with HFS.

Cystic-solid hemangioblastoma at the cerebellopontine angle: A case report

RATIONALE

Hemangioblastomas (HMGs) originating from the cerebellopontine angle (CPA) are extremely uncommon. Nevertheless, the cystic-solid form of this lesion at the above location is even rarer.

PATIENT CONCERNS

We present a 31-years old male with a right ear hearing loss of 3 months duration. He did not experience earache or discharge before the hearing loss. He; however, experienced visual acuity and dizziness. General physical examination did not yield much.

DIAGNOSES

Computed tomography and magnetic resonance imaging revealed a cystic-solid mass at right CPA. We initial misdiagnosed the lesion as an acoustic neuroma with cystic changes. Immunohistochemistry studies revealed HMG.

INTERVENTIONS

The lesion was total surgical resection via the retro-sigmoid approach.

OUTCOMES

The patient's symptomatology resolved after the surgery. Two years follow-up show no recurrence of the lesion and the patient is well.

LESIONS

Identification of feeding arteries and electro-coagulating them during the operation minimized intraoperative bleeding. The tumor should usually be dissected out whole and not piece meal fashion. Pre-operative CTA is very useful in outlining the vasculature of the tumor.

Cerebellopontine angle ependymoma in a young adult: A case report

RATIONALE

Cerebellopontine angle (CPA) ependymomas are atypical kind of ependymomas that characteristically occur in the pediatric age group. Therefore, finding a case of CPA ependymoma in a young male adult is not a common occurrence.

PATIENT CONCERNS

We present a case of a 28-year-old male who was involved in road traffic accident with suspected mild head injury. He did not have any antecedent complains before the accident.

DIAGNOSES

An incidental computer tomographic scan of the head revealed an intracranial space-occupying lesion at the left CPA. Immunohistochemical staining of the specimens indicated WHO grade II ependymoma.

INTERVENTIONS

The tumor was surgically resected and the patient was further treated with radiotherapy.

OUTCOMES

The patient recovered well postoperatively and 2 years follow-up revealed no tumor recurrence and the patient is currently well.

LESSONS

The diagnosis of ependymomas can be very challenging in adults because they are mostly mainly seen in the pediatric age group. We propose that one of the differential diagnosis of tumors in the CPA in a young adult should be CPA ependymoma.

Patient with glossopharyngeal schwannoma of cerebellopontine angle

We present a case of a man diagnosed with a rare tumour of cerebellopontine angle-glossopharyngeal schwannoma. First symptoms started at the beginning of January 2014, patient complained of tinnitus in his right ear. He had a magnetic resonance imaging (MRI) and it revealed a tumour of cerebellopontine angle. The patient underwent a surgery in September 2014. In this case tinnitus was the only symptoms of glossopharyngeal schwannoma. After surgery patient suffered from hoarseness and mild difficulty in swallowing. After analyzing the available literature it turned out that the symptoms of this tumor are not characteristic.

Mastoid foramen, mastoid emissary vein and clinical implications in neurosurgery

BACKGROUND

Mastoid emissary vein is especially important from the neurosurgical point of view, because it is located in variable number in the area of the occipitomastoid suture and it can become a source of significant bleeding in surgical approaches through the mastoid process, especially in retrosigmoid craniotomy, which is used for approaches to pathologies localized in the cerebellopontine angle. Ideal imaging method for diagnosis of these neglected structures when planning a surgical approach is high-resolution computed tomography. The aim of this work was to provide detailed information about this issue.

METHODS

We studied a group of 295 skulls obtained from collections of five anatomy departments and the National Museum. Both quantitative and qualitative parameters of the mastoid foramen were evaluated depending on side of appearance and gender. Individual distances of the mastoid foramen from clearly defined surface landmarks (asterion, apex of mastoid process, foramen magnum) and other anatomical structures closely related to this issue (width of groove for sigmoid sinus, diameters of internal and external openings of mastoid foramen) were statistically processed.

RESULTS

The most frequently represented type of the mastoid foramen is type II by Louis (41.2%). The differences between right and left sides were not statistically significant. In men there was a higher number of openings on the right side and in qualitative parameters the type III and IV predominated, whereas in women the types I and II were more frequent. In men, greater distances from the mastoid foramen were observed when evaluating qualitative parameters for defined surface landmarks. Mean size of the external opening diameter was 1.3 mm; however, several openings measured up to 7 mm.

CONCLUSIONS

Despite excellent knowledge of anatomy, however, good pre-operative examination using imaging methods and mastering of microsurgical techniques create the base for successful treatment of pathological structures in these anatomically complex areas.

Glioneuronal Heterotopia Presenting as Cerebellopontine Angle Tumor of Cranial Nerve VIII

BACKGROUND

Vestibular schwannomas and meningiomas account for the great majority of lesions arising in the cerebellopontine angle. In this report, we present a case of glioneuronal heterotopia, also known as glioneuronal hamartoma, arising from cranial nerve VIII, which is an extremely uncommon lesion. Important radiologic and surgical aspects are reviewed, which may help in early recognition and intraoperative decision making when these lesions are encountered.

CASE DESCRIPTION

A healthy 29-year-old female presented with intermittent right facial numbness. Magnetic resonance imaging showed an incidental, minimally enhancing cerebellopontine angle lesion on the right cranial nerve VII-VIII complex. The patient declined serial observation and opted for operative intervention for resection. Intraoperatively, the lesion resembled neural tissue and was continuous with the VIII cranial nerve. Pathologic analysis demonstrated mature glioneuronal tissue consistent with hamartomatous brain tissue. The patient maintained normal hearing and facial nerve function after surgery. Radiologic, surgical, and pathologic characteristics are described.

CONCLUSIONS

Ectopic glioneuronal tissue of cranial nerve VIII is a rare non-neoplastic lesion and should be considered in the differential diagnosis of unusual-appearing intracanalicular and cerebellopontine angle lesions. The congenital and benign nature of this entity makes observation a valid option for these cases, although they are so infrequent that they are often presumptively managed as vestibular schwannomas. Attempts to radically resect these lesions may result in higher rates of hearing loss or facial palsy due to their continuity with cranial nerves.

Congenital Epidermoid Cyst Presenting as Isolated Painful Trigeminal Neuropathy: Indications for Neuroimaging in the Diagnostic Process

This article reports a case of a cerebellopontine angle epidermoid cyst presenting as isolated painful trigeminal neuropathy. The indolent nature of these uncommon benign tumors leads to frequent delays in their presentation and diagnosis, with patients often initially undergoing dental procedures. This is illustrated in the present case reported here, which highlights the difficulties in identifying trigeminal neuralgia (TN), particularly in its early phases, and supports current recommendations for routine neuroimaging in suspected cases of painful trigeminal neuropathy, which, unlike classic TN, is caused by a disorder other than neurovascular compression (even in the absence of additional neurologic symptoms or signs) and is present particularly in younger patients with atypical features. Additionally, this case report offers a unique patient perspective of living with TN, with a detailed description by one of the authors of the nature of the pain and its impact.

Typical Symptoms of Normal-Pressure Hydrocephalus Caused by Choroid Plexus Papilloma in the Cerebellopontine Angle

BACKGROUND

Choroid plexus papillomas (CPPs) are rare benign intracranial tumors. We report a rare case of CPP manifesting with typical symptoms of normal-pressure hydrocephalus rather than obstructive hydrocephalus.

CASE DESCRIPTION

A 45-year-old woman presented with a 6-year history of headache and typical symptoms of normal-pressure hydrocephalus, including gait disturbance, urinary incontinence, and cognitive dysfunction, in addition to the more common symptoms of CPP, such as lower cranial nerve dysfunctions and ataxia. The CPP arose from the right lateral recess of the fourth ventricle and extended to the cerebellopontine angle. Magnetic resonance imaging did not show any radiographic evidence of obstruction of aqueduct, foramen of Magendie, or foramen of Luschka on the contralateral side. We speculated that hydrocephalus was associated with cerebrospinal fluid overproduction by the CPP originating from the choroid plexus of the lateral recess and extending laterally into the cerebellomedullary fissure (CMF). Surgical excision was performed with a trans-CMF approach. The symptoms of normal-pressure hydrocephalus disappeared. In addition to improved clinical symptoms, radiographic findings showed mitigation of ventricular dilatation.

CONCLUSIONS

The hydrocephalus was of a communicating type and caused by CSF overproduction. The lateral route of the trans-CMF approach is useful for the dissection of tumors that extend into the unilateral cerebellomedullary cistern through the CMF. This approach not only enables sufficient exposure for resection but also avoids damage to the surrounding structures.

Pandora's box: eosinophilic granuloma at the cerebellopontine angle-should we open it?

BACKGROUND

Langerhans cell histiocytosis (LCH) is a disorder of immature LCH cells, eosinophils, macrophages, lymphocytes, and multinucleated giant cells. Eosinophilic granuloma (EG) is a focal form of LCH that presents mostly in the skull, femur, vertebrae, pelvis, mandible, and ribs. Intracranial presentation of EG is very rare in the literature.

CASE DESCRIPTION

A 17-year-old boy visited our clinic with headache, dizziness, and tinnitus that were present for 2 months. Brain MRI depicted a lesion at the right cerebellopontine angle. The lesion was hypointense on T1-weighted and hyperintense on T2-weighted brain MR images. The lesion enhanced homogenously after I.V. contrast material administration. Pre-operative diagnoses were vestibular schwannoma and meningioma. Surgery was planned. Retrosigmoid approach was preferred in the surgery. The lesion was excised partially. Pathological analysis depicted cell infiltration composed of eosinophils besides histiocytes, plasma cells, and lymphocytes in different amounts. CD1a was positive yet S100 was negative. Final diagnosis was eosinophilic granuloma. Post-operative course was uneventful. The patient was referred to pediatric oncology unit, and steroid therapy was initiated. Post-operative follow-up brain MRIs showed that the lesion had regressed further than immediate post-operative images by only steroid use. In long-term follow-up, new lesions appeared on the patient's skin in multiple locations and in the sclera of his left eye. At the last follow-up (3 years post-operatively) skin and scleral lesions were noticed to have regressed spontaneously and the intracranial structures were tumor free.

DISCUSSION AND CONCLUSION

To the best of our knowledge, EG at the cerebellopontine angle has not been presented in the literature. What makes our case further unique is its negativity for S-100 antigen. Eosinophilic granuloma should be kept in differential diagnosis of mass lesions presented at the cerebellopontine angle, especially in children and young adults with high eosinophils and lymphocytes in their peripheral blood. Sole steroid trials could be conveyed in suspicious cases before any further intervention. If the lesions do not regress or enlarge with time, surgery should be considered. However, long-term follow-up of these patients is necessary since natural history of the disease has not been defined, yet.

An uncommon case of lymphoplasmacytic lymphoma in cerebellopontine angle region: Case report with a literature review

In the central nervous system, cerebellopontine angle (CPA) lymphomas are rare; few cases have been reported. Lymphoplasmacytic lymphoma (LPL) in the CPA is rarer still, and often misdiagnosed as acoustic neuroma.We report a rare case of CPA LPL-a challenging diagnosis guided by clinical presentations, radiological signs, and postoperative pathological test.A 43-year-old woman presented with headaches. Her magnetic resonance imaging revealed an abnormal homogeneously enhancing mass in the left CPA. We present detailed analysis of her disease and review relevant literature.When surgically treated, her specimen showed a typical LPL histopathology pattern. After surgery, the patient's symptoms improved greatly, and she received chemotherapy.Despite its rarity, LPL should be considered in differential diagnoses of CPA lesions that mimic acoustic neuromas.

Combined Transtemporal Access for Large (>3 cm) Meningiomas of the Cerebellopontine Angle

OBJECTIVES: Large meningiomas of the cerebellopontine angle present a formidable surgical challenge due to tumor vascularity, neural attachment, and brain stem compression. The purpose of this paper is to present our use of the combined transtemporal approach in the surgical treatment of 29 large meningiomas.

STUDY DESIGN AND SETTING: Twenty-nine patients with large meningiomas of the CPA were surgically treated through a combined retrosigmoid-transpetrosal-transcochlear approach at our tertiary care academic medical center from July 1995 through July 2004. Data was collected from a retrospective medical records review.

RESULTS: Total tumor removal was achieved in 19 of 29 (67%) of the patients and the facial nerve was anatomically preserved in 26 of 29 (89%) of the cases. Cerebrospinal fluid leakage was seen in 3.5% of the patients and additional transient cranial nerve deficits were noted in 14% of the cases, but no significant neurologic sequelae occurred. Of the 10 patients with residual tumor, 6 have been stable without growth, 2 were treated with reoperation for regrowth of disease, and 2 were controlled with localized radiotherapy.

CONCLUSIONS: This combined lateral transtemporal approach provided wide exposure to the cerebellopontine angle and optimized the surgical extirpation of 29 large meningiomas presented in this series.

Pontomedullary white epidermoid: a rare cause of tinnitus

Intracranial epidermoid cysts are relatively rare congenital inclusion cysts. They are the third most common cerebellopontine angle cistern mass after vestibular schwannoma and meningioma. White epidermoid is a rare variant. We present the first case, to our knowledge, of a white epidermoid cyst anterior to the pontomedullary junction, emphasising its imaging appearance, location and the importance of pre-operative diagnosis, which may reduce operative complications.

[Bilateral cerebellopontine angle lipoma in an asymptomatic patient: a case report]

We present here an asymptomatic case of a bilateral cerebello-pontine angle lipoma incidentally diagnosed by magnetic resonance imaging. Intracranial lipomas are rare and comprise just 0.1-1.5% of all intracranial tumors, and are mostly located in the corpus callosum. Cerebello-pontine angle (CPA) or internal acoustic canal (IAC) locations, on the other hand, are rather rare, and usually unilateral. Bilateral locations, as with the case presented here, were reported in only three cases in the literature. Cerebello-pontine angle and IAC lipomas typically infiltrate the neighboring cranial nerves (5, 7 and 8), causing progressive neurological deficits in 95% of cases. However, cases of bilateral CPA/IAC lipomas similar to this case are interesting because of their being asymptomatic.

Cerebellopontine angle tumor in a patient with a maternally inherited SDHD gene mutation

Acoustic neuromas are the most common tumor in the cerebellopontine angle (CPA) but are rare in the general population. Paragangliomas are rarer still and, in a minority of cases (20%), are known to be caused by errors in the SDHD gene. Mutations in this gene are highly penetrant when inherited paternally but not maternally. We present the first reported case of a patient with a CPA tumor and a maternally inherited SDHD gene mutation.

Giant vertebro-basilar aneurysm: an unusual cerebello-pontine angle lesion

Acoustic neuromas (vestibular schwannomas) comprise more than 90 per cent of all cerebello-pontine angle (CPA) lesions. We present a rare case of a giant vertebro-basilar aneurysm presenting as a CPA lesion. The general condition of the patient precluded the completion of the magnetic resonance (MR) sequences. The clinical and limited radiological results (T2 images alone, the features of which were not specific) initially did not lead to a specific diagnosis. To obtain further radiological information a computed tomography (CT) scan with contrast was performed and this revealed the lesion to be an aneurysm. The diagnostic difficulties and the treatment dilemmas of such a lesion are discussed. The importance of fine, axial, post-contrast CT arteriography with three-dimensional reconstruction, MR angiography and digital subtraction angiography are highlighted. The limitations of MR imaging in patients with CPA lesions are discussed.

Calcified vestibular schwannoma in the cerebellopontine angle

Although vestibular schwannoma is a common tumor in the cerebellopontine angle, calcified vestibular schwannoma is rare. A 59-year-old woman with sudden onset epileptic seizures, was referred to Hokkaido Neurosurgical Memorial Hospital. Neurological examination revealed left Bruns nystagmus, left deafness and left cerebellar ataxia. Brain MRI revealed a mass, about 3cm in diameter, in the left cerebellopontine angle. The mass showed heterogeneous intensity on T1- and T2-weighted and fluid-attenuated inversion recovery (FLAIR) images. Hydrocephalus was seen. On CT scan, the tumor was calcified. Preoperatively, vestibular schwannoma, meningioma, cavernous hemangioma, or thrombosed giant aneurysm were considered as differential diagnoses. The pathological diagnosis was schwannoma. For a calcified mass in the cerebellopontine angle, vestibular schwannoma should be considered in the differential diagnosis to plan appropriate treatment strategies.

Treatment of a Facial Nerve Neuroma with Fractionated Stereotactic Radiotherapy

BACKGROUND

Facial nerve neuromas are extremely rare and are often mistaken for acoustic neuromas when located near the vestibular nerve. Usually presenting with facial weakness and hearing loss, facial nerve neuromas of the cerebellopontine angle have commonly been managed by surgery. We present the first reported case of a facial nerve neuroma treated with fractionated stereotactic radiotherapy (FSRT).

METHODS

The patient was a 40-year-old woman who presented with tinnitus, dizziness and decreased hearing that was associated with a right intracanalicular mass on magnetic resonance imaging (MRI). She underwent a middle fossa craniotomy only to reveal a facial nerve tumor rather than an acoustic neuroma that was not resected due to the high risk of facial paralysis. Following surgery, her facial function worsened and was associated with tumor enlargement on MRI. She was referred for FSRT and received 54 Gy in daily 1.8-Gy fractions with a prescription isodose line of 90%.

RESULTS

Three months after treatment she had no worsening of her pretreatment symptoms, and at the 1-year follow-up, she experienced facial weakness improvement accompanied by an absence of tumor growth on MRI. These clinical and imaging findings persisted at 48 months of follow-up.

CONCLUSION

In the first report of a facial nerve neuroma treated with FSRT, this treatment resulted in excellent long-term (4-year) tumor control with improvement of pretreatment symptomatology and absence of morbidity. This report demonstrates the potential for using FSRT to treat facial nerve neuromas of the cerebellopontine angle that could otherwise be associated with significant operative morbidity.

[Diagnostic problems of rare cerebellopontine angle tumors]

Astrocytoma (neuroepithelial tumor) determine about 25% all the cerebroma but their original location in cerebellopontine angle is seldom. In case of this kind of tumors in this place, the symptoms can be non-characteristic and similar to these, which appear in the acoustic neurinoma. The most important in case of this diagnosis is both that this tumors can infiltrate of the brain tissues and the fact that they can transformate toward the anaplastic astrocytoma or glioblastoma multiforme (very malignant tumors).

MATERIAL AND METHODS

[corrected] A rare case of astrocytoma presenting as a cerebellopontine angle tumor is discussed. The special characteristics of this tumor and unusual clinical course are disscused.

CONCLUSION

The early diagnosis of the astrocytoma increases the patient's chance on convalescence and limits extension of the operation, and consequently of the neurological complication.

Atypical CT and MRI aspects of an epidermoid cyst

We report a case of an unusual epidermoid cyst (EC) of the cerebellopontine angle that appeared hyperdense on computed tomography (CT) scanning, hyperintense on T1-weighted MR images and hypointense on T2-weighted magnetic resonance (MR) images. Diffusion-weighted imaging showed a hypointense lesion. We discuss imaging characteristics of ECs, explain the atypical findings in our case and confirm that the signal seen on diffusion-weighted images in the EC is related to a T2 effect.

Hydatid cysts of the internal acoustic canal and jugular foramen

Brain involvement with hydatid disease occurs in 1-2% of all Echinococcus granulosus infections. Cerebral hydatid cysts are usually supratentorial, whereas infratentorial lesions are quite rare. Here we report a 19-year-old man with hydatid cysts in the right cerebellopontine cistern with the involvement of internal acoustic canal and jugular foramen. The patient presented with signs of increased intracranial pressure and multiple cranial nerve palsies. Surgery was performed in the semi-sitting position using a lateral suboccipital approach for a right-sided craniotomy. Magnetic resonance imaging clearly demonstrated cisternal, neural and vascular relationships which aided in intact surgical removal of the lesion using microsurgical techniques. Total removal without rupture should be the surgical goal in all hydatid cysts.

Cerebellopontine angle lipoma with extracranial extension

Lipomas of the cerebellopontine angle (CPA) are rare. A recent literature review identified only 98 reported cases of CPA lipoma. We present here a case of CPA lipoma in a 28-year-old woman who was admitted to our hospital with hearing loss in her left ear. Computed tomography scan and magnetic resonance imaging revealed a CPA mass lesion with extracranial extension around the left internal carotiol artery. The patient was operated on in the sitting position via a right suboccipital craniectomy. The intracranial part of the mass was partially removed. Histopathological examination resulted in a diagnosis of lipoma. Surgical treatment of CPA lipomas is rarely indicated, and the aim of surgery must be decompression of neural structures.