A Surprise Diagnosis from a Unilateral Hearing Loss and Vertigo Case from Cerebellopontine Angle Tumor

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doi: 10.62055/plaebkdlzprh

ABSTRACT

Background

Meningiomas are generally benign intracranial tumors that arise from the dural coverings of the brain. They represent approximately one-third of all primary intracranial tumors and about 10-15% of cerebellopontine angle (CPA) tumors. Meningiomas develop from arachnoid cells and have been previously observed to be slow-growing. Despite their benign classification, these tumors can impact cranial nerves leading to a myriad of symptoms including hearing loss, imbalance or vertigo, tinnitus, and diminished facial sensation. Technology such as computerized tomography (CT) and magnetic resonance imaging (MRI) are vital tools in the definitive diagnosis of CPA meningiomas.

Case Report

A 48-year-old Asian female presented for a comprehensive eye examination. The patient stated that she experienced some vertigo and hearing loss in her right ear. An audiology examination a few months prior found no hearing loss and an ophthalmic examination revealed normal ocular health in both eyes. A consultation to an Ear, Nose, and Throat (ENT) specialist was initiated. The ENT examination was deemed normal, but persistence of symptoms without improvement prompted an MRI imaging. The MRI revealed a CPA meningioma that compressed the cerebellum and pontine with internal auditory canal (IAC) involvement.

Conclusion

Diagnosing CPA meningioma is rare in ophthalmic practices due to nonspecific symptoms that are not related to ocular health. Often, there is a long interval between the onset of symptoms and the final diagnosis of the tumor. This case highlighted the vigilance of both the patient and health care provider in achieving a correct diagnosis for the patient.

Keywords: intracranial meningioma, cerebellopontine angle (CPA) meningiomas, unilateral hearing loss, tinnitus, vertigo and imbalance, cerebellopontine angle (CPA) meningiomas with internal auditory canal (IAC) involvement

INTRODUCTION

The etiology of unilateral hearing loss and vertigo is multifactorial and diverse. Most common etiologies include seasonal allergies, Meniere’s disease, trauma or injury to the head, heredity, viral or bacterial ear infection, smoking, idiopathic, labyrinthitis, microtia, mastoiditis, autoimmune diseases, anterior inferior cerebellar artery stroke, and any compression of the vestibulocochlear nerve either by blood vessels such as arteriovenous malformation or by any neoplasm.¹ In 23 meta-analysis studies, the incidence of vestibulocochlear neoplasm was reported approximately 2.3%.² We describe a case of cerebellopontine angle (CPA) meningioma in a patient presenting with symptoms of unilateral progressive hearing loss and vertigo.

CASE REPORT

A 48-year-old Asian female presented to the eye clinic for a comprehensive eye examination. The patient stated that about six months prior, she started to experience chronic headaches, right ear hearing loss, problems with balance, and vertigo. There was no history of trauma or ear infection. The patient was a non-smoker. Initially, the patient saw her primary care provider (PCP) and was diagnosed with allergies. The allergy treatments did not resolve her symptoms. At a prior audiology consultation, the patient’s pure tone audiometry and speech discrimination testing showed normal hearing and her ears were in excellent health. Persistence of symptoms without improvement prompted an eye consultation. She noticed that when she tilted her head to the left or right, she lost her balance. Her last eye examination was 3 years prior. Her ocular history was remarkable for dry eye and chronic allergic conjunctivitis. Medical history was remarkable for hyperlipidemia, chronic allergies, migraine headache, and vitamin D deficiency. She was taking atorvastatin calcium, vitamin D supplement, multivitamin supplement, omega-3 supplement, cetirizine, diphenhydramine, meclizine, ketotifen ophthalmic solution both eyes (OU) twice daily, artificial tears three times OU, and Refresh PM ointment at bedtime OU.

Ocular examination showed that the patient had mild myopia and presbyopia with best corrected vision 20/20 right eye (OD), left eye (OS), and OU. Her eye movements were full and smooth. There was no nystagmus or double vision in any field of gaze. Pupils were equal, round, and reactive to light without any afferent pupillary defect. Confrontation fields were full with finger counting OD, OS. Intraocular pressures were 14 mmHg OD and OS. Anterior segment was remarkable for dry eyes. She was compliant with her dry eye treatment and her symptoms were stable. Dilated fundus examination showed 0.35 cupping OD and OS, healthy macula, vasculature, and retina OD and OS (Figure 1).

Differential diagnoses considered for her symptoms were Meniere’s disease, viral or bacterial ear infection, idiopathic, labyrinthitis, microtia, mastoiditis, autoimmune diseases, genetic disorders, anterior inferior cerebellar artery stroke, and any compression of the vestibulocochlear nerves such as vestibular schwannomas or arteriovenous malformation.

After a thorough discussion, the patient was referred to her primary care provider (PCP) for an Ear, Nose, and Throat (ENT) consultation to further investigate her symptoms. ENT reported that the patient did not have any otologic or neurological deficits. All cranial nerves, including trigeminal and facial nerves were intact. Long tract signs and cerebellar function were preserved. Romberg and coordination testing were normal. There was no derangement in tandem walk, no pathological gaze-evoked nystagmus (GEN), no Bruns nystagmus, no abnormal head impulse test (HIT), or impaired vestibulo-ocular reflex (VOR). A few months later, during a follow up visit, the patient reported that her symptoms were progressively worse. She was almost completely deaf in her right ear and her vertigo became more unstable. The patient was referred to the PCP for MRI imaging.

Figure 1. Dilated fundus photo of OD (A) OS (B).

A Gadolinium contrast-enhanced MRI revealed the presence of a hemispheric broad base mass located in the cerebellopontine angle. It measured at 3.0 x 2.9 x 2.9 cm in size and demonstrated mass effect onto the right cerebellum and adjacent pons with a dural tail that invaded into the right internal auditory canal (IAC) (Figure 2).

Figure 2. MRI of the brain, axial view(A) and coronal view (B) visualized right CPA meningioma (blue arrow).

Urgent neuro-otology and neurology consults were initiated. The patient subsequently underwent retro-sigmoid craniotomy for a complete tumor excision. The histopathology report confirmed the impression of meningioma. The patient is currently under neurology surveillance every 6 months for any tumor recurrence.

DISCUSSION

One of the possible etiologies of unilateral progressive or sudden hearing loss and vertigo is a neoplasm in the CPA.¹ The CPA is a triangular cisternal space within the posterior fossa formed at the junction of the cerebellum, pons, and medulla.³ It is an important landmark that has intricate relationship with multiple cranial nerves from V – XI, the cerebellum flocculus, the choroid plexus, anterior inferior cerebellar and superior cerebellar arteries.³ Meningiomas are the second most common neoplasm in the entire brain and they account for about 10-15% of CPA lesions.^4-8 They are slow-growing tumors that arise from arachnoid cells located on the inner surface of the dura.^9-10

Diagnosing CPA meningioma is challenging due to the diverse manifestations from chronic headaches, hearing loss, dizziness, ataxia, imbalance or vertigo, disequilibrium, tinnitus, diminished facial sensation, and seizures.^3-4,7,10-14 The presentation of symptoms are non-specific and depend on the size, location, and involvement of the meningioma (see Table 1).

Table 1. Presenting symptoms of CPA meningioma patients in different studies4-6,11,13,14,15. Note: (*Bu et al combined hearing loss and tinnitus as one symptom.)

The identification of CPA meningioma is often delayed from initial presentation due to the misleading symptoms of the condition. Typically, meningiomas do not show symptoms until they have grown to a larger size. As they grow larger, meningiomas can compress the surrounding brain tissue, cranial nerves, or arteries and cause significant damage to those vital structures.^6,13 CPA tumors can displace cranial nerves depending on the origin of the dural site.⁶ CPA meningioma involving the IAC can result in sensorineural hearing loss by either direct injury of the vestibulocochlear nerve or interrupting blood flow to the vestibulocochlear nerve.¹³ If the facial cranial nerve is impacted, facial palsy and dysfunction can manifest.

Larger CPA meningiomas can compress the trigeminal nerve which results in a reduced corneal reflex and facial hypoesthesia involving facial or eye twitching. Laird et al found 50% of patients with meningiomas of the CPA had decreased corneal reflex, 25% had facial hypesthesia, and 15% had facial weakness secondary to compression of the trigeminal nerve.⁴ Ocular complaints are rare but more visible if they become true ocular dysfunction. Diplopia, especially divergence insufficiency where double vision is greater at distance than near, can occur if CPA meningioma affects the abducens nerve. Blurry vision can happen in larger CPA meningiomas that compress the brainstem leading to fourth ventricle obstruction causing papilledema and optic atrophy.^4,15 Laird et al found 10% of patients had papilledema and Babinski’s sign.⁴ If a meningioma is left undiscovered in the CPA, it can lead to severe morbidity and can be life-threatening such as hydrocephalus, respiratory depression, and death.¹⁰

Correct diagnosis is made based on careful history, physical examination, audiometric, and radiological imaging.³ Patients who have CPA meningiomas may show audio-vestibular symptoms including abnormal head impulse test (HIT), impaired vestibulo-ocular reflex (VOR), and pathological gaze-evoked nystagmus (GEN).^16-17 The medial vestibular nucleus and cerebellar flocculus hold the neural integrator for horizontal eye movement. The compression of the cerebellum and/or brainstem result in the flocculus, vestibular nucleus, and the brainstem dysfunctions and would give rise to abnormal GEN, HIT, and VOR.^16-17

HIT also plays an important role in detecting CPA meningioma.¹⁶ Kim et al study found 80% of patients who had CPA compressing lesions had bilateral abnormality in HIT versus 8% in non-lesion group.¹⁷ Also, they found head impulse VOR gain were significantly lower in the CPA lesion group vs non-lesion group.¹⁷ VOR’s function is gaze stability by coordinating eye movement to maintain foveal fixation of images in order to provide clear vision and balance during head movement. In a healthy person, the VOR gain is a 1 to 1 ratio with head movement. If the magnitude of the eye movement is less than that of the head movement then the VOR gain is reduced. HIT is used to help identify an impaired VOR in vertigo patients. During the HIT, the patient is asked to fixate his or her eyes on the examiner’s nose. The examiner, then, briskly rotates the patient’s head to the left or to the right at about 15-20 degrees while focusing on the patient’s eyes for any corrective or compensatory saccade (CS).¹⁸ In the normal response, the patient’s eyes remain on the target, and it should not exhibit any CS. In the abnormal response, the eyes are dropped off the target when the head turns toward the affected side, followed by eyes moving back to the target. This movement generates a CS which indicates a VOR deficit and is considered a positive HIT.¹⁸

Other findings included 39% of CPA lesion group exhibited GEN and 29% displayed a contralesional spontaneous nystagmus.¹⁷ Similarly, Laird et al study also reported spontaneous nystagmus occurred in 30% of the patients.⁴ GEN is defined as jerky nystagmus induced by moving the eyes to an eccentric gaze away from primary position. Physiologic GEN or end-point nystagmus is normal eye movements that occur at gaze angles greater than 40 degrees.¹⁹ It usually beats at a low amplitude and frequency, un-sustained duration, and relatively symmetric in both the abducting and adducting eyes. Pathological GEN is defined as an asymmetric nystagmus at an eccentric gaze of 30 degrees or less. It is characterized by slow frequency but large amplitude nystagmus when looking toward the side of the CPA lesion and rapid but small amplitude nystagmus when looking to the contralateral side.¹⁹ Asymmetrical GEN has been used to identify any lesion or stroke in the CPA and it is observed in 5-12% of large CPA lesion patients.¹⁶

CTand MRI are vital tools in the successful diagnosis of CPA meningiomas.^3,8,14 A Gadolinium contrast-enhanced MRI is the gold standard for diagnosis of CPA meningioma while high-resolution CT is useful for the assessment of bone involvement.^3,8,9 A distinctive characteristic image of meningioma is a hemispheric broad-based mass or ice-cream cone shape with a dural tail extension. This distinctive characteristic in the presence of an enlargement of the IAC is highly suggestive of meningiomas.^3,8,11,13-14 Contrast-enhanced CT reveals a homogenous enhancement pattern of a hyperdense mass relative to surrounding brain tissue.⁴

The World Health Organization (WHO) classifies meningiomas by histological grade I, II, and III. Grade I is designated for benign lesions and makes up about 80% of the cases.^5,11 Grade II makes up around 17-18% and is labeled as atypical.^11-12 Grade III is malignant histology and comprises the last 1-2%.¹¹ Meningiomas are rare in children and teenagers. The risk of developing meningioma increases with age; the mean age at diagnosis is in the fifth decade of life.^5,6,10,11 They are more commonly found in females than males.^5,10-11 There is a link between hormones and meningiomas especially with menstrual cycles and pregnancy.¹¹ Ionizing radiation exposure is linked to an increased risk of meningiomas.^10-11 Neurofibromatosis Type 2 is the most common genetic disorder that is associated with meningioma growth.^3,10-11 Werner’s syndromes are 36 times more likely to develop meningioma.¹¹ Obesity also has a positive association with meningioma risk.^10-11

Treatment options for CPA meningiomas include observation, radiotherapy, microsurgery, and chemotherapy.^3,11 Observation can be suitable for elderly or medically unstable patients and in small tumors with little or no evidence of growth or lacking the manifestation of symptoms.^3,11 Observation requires serial imaging and frequent follow up. Radiation therapy such as gamma knife, cyber knife, and other types of linear accelerator are treatments of choice for unresectable tumors, small size tumors, or in adjunct as a prevention of postoperative residual and recurrent tumors.^3,11,15 A high dose of targeted radiation is delivered directly to the tumor to halt the growth or shrink the tumor.³ Recent studies found that radiotherapy had limitations of low tumor control rate, post-treatment brain edema, and tissue adhesions which can hinder the further treatment options.^9,12

Indications for surgery would be the presence of a neurological deficit due to brain stem, cerebellum, or cranial nerve compression.^11,13 The goal is to completely remove all the tumor network while preserving cranial nerve functions.^3,14 Historically, surgeries within the CPA were associated with high mortality rate.⁴ Despite advances in neurosurgery, the surgical procedure for CPA meningiomas involving the IAC remains challenging due to the deep location, narrow surgical field, and compression of many important neurovascular structures that are close to the brainstem and multiple cranial nerves.^5,13-15 The collaboration of a multidisciplinary team of specialties such as neurology, neurosurgery, neuro-otology, radiology, and audiology is prudent to yield an acceptable morbidity surgical outcome.^3,6

Surgical approach depends on the tumor size, location of origin, and pre-operative neurologic function of the patient, the probability of hearing and facial nerve preservation and other potential complications.^12-15 Retro-sigmoid or suboccipital approach is the most versatile and widely used technique that provide an adequate surgical field as well as allowing hearing preservation.^3,7,13-14 This surgical technique is often used for medium- to large-sized tumors that compress on the brain tissues.¹⁴ Surgical complications include dysfunction of auditory nerve, facial nerve, trigeminal nerve, and as well as posterior cranial nerve damage.¹³

Voss et al found that 70% of patients had hearing loss post-operatively. Around 50% of patients experienced unsteadiness followed by 42% with tinnitus and 40% with headaches. About 20% experienced facial numbness; 12.5% had hemifacial spasm; 10% had vertigo and dysphagia respectively. On average, these symptoms lasted for 25 months post operatively.⁶ Other complications include cerebrospinal fluid leaks, infection, meningitis, dizziness, double vision, difficulty closing eyelids, dry eyes, dry mouth, stroke, and death.^3,7,9 Posterior cranial nerve dysfunction includes dysphagia, alter the sense of taste, hoarseness, dysarthria, and weakened cough reflex.^4,9,13,15 Chemotherapy is only used to treat atypical or malignant meningioma subtypes that cannot be treated with radiation or surgery alone.¹⁵ Meningiomas have a broad five-year-recurrence rate ranging from 7% in grade I up to 90% in grade III.²⁰ The risk of recurrence is higher in incompletely resected tumors.²⁰ Overall, the prognosis for CPA meningiomas is good. The ten-year survival rate for benign meningiomas is 81.4%, while malignant meningiomas is about 57%.²⁰ Long-term follow up with serial imaging is necessary to monitor recurrence.³

CONCLUSION

Diagnosing CPA meningioma is rare in ophthalmic practices because it has a variety of nonspecific symptoms that can be misleading. Often, there is a long interval between the onset of symptoms and the final diagnosis of the CPA meningioma. When evaluating patients presenting with progressive unilateral hearing loss and vertigo without a history of trauma or infection, it is crucial to inquire further for any abnormal symptoms such as unilateral facial hypoesthesia, eye twitching, decreased cornea reflex, or diplopia. Appropriate oculomotor assessments of different eye movements including pursuit, saccades, gaze holding function such as GEN, HIT, and VOR should be included in the evaluation to rule out CPA suspicion. The important point of these tests is to check for the adequacy of eye movements. Any impairment in oculomotor function can serve as a vital diagnostic clue to a neurological condition such as CPA meningioma and should prompt further multidisciplinary diagnostic work up. Timely detection and treatment are paramount. Delayed diagnosis and treatment are associated with high morbidity and mortality outcomes.

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Thanh T. Le OD, MPH, FAAO

South Texas Veterans Health Care System | San Antonio, TX

Dr. Le received her optometry degree from Pennsylvania College of Optometry at Salus University in 2005. After graduation, she served in the U.S. Navy until 2011. She’s currently working at the South Texas Veterans Health Care System in San Antonio, Texas. Dr. Le is an adjunct assistant professor at several optometry schools.

Dipti Singh OD MPH FAAO ABCMO

Audie Murphy VA Hospital | San Antonio, TX

Dr. Dipti Singh graduated from Southern College of Optometry in 2001. After graduation, she completed Residency in Primary Care Optometry with Emphasis in Ocular Disease at James H. Quillen Mountain Veterans Affairs Medical Center in 2002. She is currently working at the South Texas Veterans Health Care System in San Antonio, TX. Dr. Singh is currently the Ocular Disease Coordinator for Residency in Brain Injury Vision Rehabilitation and Ocular Disease at the Audie Murphy VA Hospital.