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 Table of Contents  
CASE REPORT
Year : 2020  |  Volume : 26  |  Issue : 1  |  Page : 51-53

Prominent auditory and balance disturbances in a patient with trigeminal nerve schwannoma


1 Audiology and Speech Pathology Programme, School of Health Sciences, Universiti Sains Malaysia, Kelantan, Malaysia
2 Department of Otorhinolaryngology, School of Medical Sciences, Universiti Sains Malaysia, Kelantan, Malaysia

Date of Submission18-Jul-2019
Date of Acceptance04-Oct-2019
Date of Web Publication19-Feb-2020

Correspondence Address:
Dr. Rosdan Salim
Department of Otorhinolaryngology, School of Medical Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan
Malaysia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/indianjotol.INDIANJOTOL_80_19

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  Abstract 


Trigeminal nerve schwannoma, a rare type of schwannoma, can be challenging to be diagnosed. Its initial clinical presentations may be subtle in nature but could deteriorate rapidly once the mass is large enough to compress the surrounding nerves. In this article, we report a case of a 55-year-old Malay female who complained of only numbness (without other symptoms) during her visit in the year 2014. As such, the otological findings were unremarkable. In the year 2017, her condition was worsening to the extent that she was not able to walk or stand independently and her hearing had dropped to a profound level in the right side. Low gain on the anterior and lateral right semicircular canals was found in video head impulse test, suggesting the hypofunction of the right semicircular system. The magnetic resonance imaging was carried out, and the presence of mass at the trigeminal nerve was confirmed. It is important to highlight that the auditory and balance can be prominently affected in trigeminal nerve schwannoma. Audiological and vestibular assessments are important to complement the diagnosis and prognosis of the patient.

Keywords: Auditory, balance, hypofunction, trigeminal nerve schwannoma, vestibular


How to cite this article:
Sakeri NS, Zakaria MN, Salim R, Othman NA. Prominent auditory and balance disturbances in a patient with trigeminal nerve schwannoma. Indian J Otol 2020;26:51-3

How to cite this URL:
Sakeri NS, Zakaria MN, Salim R, Othman NA. Prominent auditory and balance disturbances in a patient with trigeminal nerve schwannoma. Indian J Otol [serial online] 2020 [cited 2020 Mar 29];26:51-3. Available from: http://www.indianjotol.org/text.asp?2020/26/1/51/278740




  Introduction Top


Trigeminal nerve schwannoma, an uncommon slow-growing mass of the Schwan cells myelinating the trigeminal nerve, is a rare but the second most common type of schwannoma following acoustic schwannoma.[1] Its occurrence ranged from 0.07% to 0.3% of all intracranial tumors and 0.8%–5% of intracranial schwannomas,[2] and it is far less common in a malignant form.[3] It usually happens during the third or fourth decade of life.[1] Trigeminal nerve is the fifth cranial nerve (CN V) and the largest of all. The nerve further divides into three branches of nerves: ophthalmic, maxillary, and mandibular. The trigeminal nerve has two types of nerve fibers. A sensory fibers that innervate sensory information to the face, mucous membrane and other structures of the head. Second, a motor innervation to the mandibular muscles of mastication. If the mass is large enough, it would compress the surrounding nerves, and the affected individuals would have symptoms mimicking that of acoustic neuroma. However, its initial presentations can be unique and distinguishable with other types of schwannoma. In this article, we report a case of trigeminal nerve schwannoma with subtle symptoms initially; but then, prominent auditory and balance problems were developed.


  Case Report Top


In 2014, a 55-year-old Malay female came to Otorhinolaryngology Clinic, University Hospital with the main complaint of facial numbness on the right side. The numbness has been persistent for 2 months, but the condition was not worsening. The numbness was also felt on the right side of the tongue. From history, there was no report of trauma to the head or any occurrence of fever and no history of herpes infection involving the face area before the numbness. She also complained of reduced sensation (numbness) periorally or perinasally and has no history of dental extraction or fall. There was no ear and nasal symptoms reported. She has a family history of cancer whereby her sister died of cancer. Even though the CNs were found to be grossly intact, reduced sensation was reported for the two branches of trigeminal nerve (CN V): maxillary nerve (V2) and mandibular nerve (V3). Ear, hearing, and balance examinations' results were unremarkable. Her hearing was in the normal range bilaterally [Figure 1]a.
Figure 1: Pure tone audiometry of the patient conducted in the year 2014 (a) and in the year 2017 (b)

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In 2017, while her hearing in the left ear remained intact, she reported that the hearing in the right ear had deteriorated tremendously. There were no other ear symptoms such as ear discharge or ear pain, and no nasal symptoms reported. Raining-like tinnitus sound was on and off in the right ear. She had no vertigo but reported a feeling of floating and imbalance while walking. As such, she required minimal assistance during walking or standing as she prone to fall to the right side when she stands or walks. Two months later, her balance and gait conditions worsened, in which she had to be assisted to stand or walk as she would fall to the right side. She also required a wheelchair to move around.

The otological examination revealed an intact tympanic membrane in both ears. Hearing assessment showed normal hearing in the left side and profound sensorineural hearing loss in the right side [Figure 1]b. Videonystagmography (VNG) and video head impulse test (VHIT) were also conducted. There was no spontaneous nystagmus in the gaze assessment. In saccade assessment, the velocity and accuracy of the vestibular–ocular reflex (VOR) reduced during the rightward eye movement, gain was not in the normal range during smooth pursuit, and optokinetic was normal. VNG suggested that there might be central involvement of the imbalance. VHIT showed low gain of the VOR on the right anterior canal (0.57) and lateral canal (0.79), implying hypofunction on the two canals and/or superior vestibular nerve.

Magnetic resonance imaging (MRI) was conducted, and the presence of a broad-based mass, measuring of 2.3 cm × 3.64 cm × 4 cm, in the right cerebellopontine angle was clearly seen [Figure 2]. The mass was reported extending into the right cavernous sinus producing a dumbbell-shaped appearance and may have extended into the internal acoustic meatus due to slight widening of the entry of Internal acoustic meatus (IAM) (6.0 vs. 6.1 cm [on the normal side]). The mass is causing the “mass effect” pushing the right temporal lobe and right posterior cerebral artery superiolaterally and brainstem toward the left. MRI impression includes a right extra-axial cerebellopontine angle mass, and differential diagnosis includes trigeminal schwannoma.
Figure 2: Magnetic resonance imaging of the patient (a broad-based mass in the right cerebellopontine angle is clearly seen)

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  Discussion Top


Studies have shown that the most common clinical presenting symptom of the trigeminal nerve schwannoma is facial pain, which is typically described as burning sensation on the face.[2],[3] Nevertheless, the burning sensation was not reported by the patient. Her main complaint was the feeling of numbness on the right side of the face and tongue. The numbness alone, even though was not worsening for few years, should be an alarming symptom for further investigation as numbness is a common symptom that might indicate the presence of a tumor.[2] The auditory and balance symptoms were developed very much later from the initial complaint. This suggests that the broad mass has started to impinge on the vestibulocochlear nerve as well. Her hearing had deteriorated to profound loss only after 3 years. Nevertheless, according to Ganesan et al.,[4] for such tumors to give effect on hearing is very scarce. She also noticed the presence of tinnitus in her right ear intermittently. Her balance and gait were severely impaired 3 years following the numbness. Thus, it is worth to highlight that even though the trigeminal nerve schwannoma rarely affects hearing and balance, there is always the possibility for such tumor to affect those systems, and due to subtle presentation of symptoms at the initial stage, it is very common that the trigeminal nerve schwannomas are not picked up until at much later stages.[4]

Even though there are some similarities, the presenting symptoms of trigeminal nerve schwannoma can be different from that of acoustic neuroma. In the early stage of acoustic neuroma, the most common complaints are gradual reduction in hearing and the presence of tinnitus in the ear.[5] Occasionally, there are complaints of dizziness, swaying, imbalance, and other vestibular-related symptoms, although the true vertigo is very rarely reported.[5] It is only at the later stage, the numbness on the face and/or muscle weakness and occasionally ear and/or headache were reported by the patients.[5] As in this case, numbness was the initial symptom presented, and hearing loss and imbalance were not reported until at much later years, which is more likely to be trigeminal nerve schwannoma.

A set of test battery involving hearing test, stapedial reflex, auditory brainstem response, and vestibular-evoked myogenic potential (VEMP) is recommended to assist in determining the likelihood of the problem beyond the cochlea.[6] VHIT is a good choice of vestibular test as it is quick to perform because the other bedside testing were not possible to be administered as the patient was hardly able to stand still on her own. The results from the VHIT suggest the presence of pathology involving the lateral and anterior canal of the right semicircular canals or superior vestibular nerve and have further evidence that VHIT is quite sensitive to check hypofunction of the canal due to central disorder as such the trigeminal nerve schwannomas compressing the nerve.


  Conclusion Top


Even though the trigeminal nerve schwannoma is the second most common tumor following acoustic neuromas, it is a rare type of schwannoma. The limited presenting clinical symptoms at the initial stage may also limit the extensive medical investigations that one should have. It is also appropriate to highlight that the trigeminal nerve schwannoma may cause prominent impairment of hearing and balance. Thus, these should be alarming symptoms for otologists and audiologist to the possible cause of the auditory and imbalance symptoms due to the central pathology. VHIT is a sensitive test for such central pathology as the tumor may impair the nerves. Perhaps, conducting VEMP may offer a complete view to determine the status of the vestibular nerve including the inferior vestibular nerve.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Kashyap P, Dave D, Melmane P, Bhate A. Case report trigeminal nerve schwannoma. Int J Res Med Sci 2016;4:1739-41.  Back to cited text no. 1
    
2.
Agarwal A. Intracranial trigeminal schwannoma. Neuroradiol J 2015;28:36-41.  Back to cited text no. 2
    
3.
Stone JA, Cooper H, Castillo M, Mukherji SK. Malignant schwannoma of the trigeminal nerve. AJNR Am J Neuroradiol 2001;22:505-7.  Back to cited text no. 3
    
4.
Ganesan P, Sankaran P, Kothandaraman PP. A rare case of hearing impairment due to cerebello-pontine angle lesion: Trigeminal schwannoma. J Int Adv Otol 2015;11:170-2.  Back to cited text no. 4
    
5.
Kharkheli E, Shurigina L, Davitashvili O, Tushishvili M, Chibalashvili N, Korteweg M, et al. Acoustic neuroma diagnosis. Georgian Med News 2011;3:21-7.  Back to cited text no. 5
    
6.
Valame DA, Gore GB. Vestibular nerve compression : Role of auditory brainstem response and cervical vestibular evoked myogenic potentials. Int J Otorhinolaryngol Head Neck Surg 2017;3:749-54.  Back to cited text no. 6
    


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  [Figure 1], [Figure 2]



 

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