PainJournal.net

     Clinical Journal of Pain for

Healthcare Professionals and Patients

 Signs and Symptoms of Temporomandibular Disorders and Tinnitus Secondary to Acoustic Neuroma:

The Importance of the Differential Diagnosis   

Maurício A. Bisi^3,4, DDS; Caio M. P. Selaimen^1,2, DDS, MSc;

Karen D. Chaves^3,4, CD, MSc, PhD; Melissa C. Bisi (Undergraduate Student)⁵;

Márcio L. Grossi^1,2, CD, MSc, PhD 

¹Faculty of Dentistry, Catholic University of Rio Grande do Sul - PUCRS, Brazil

²Temporomandibular Disorders Research Unit - CNPq, Brazilian Government

³Brazilian Dental Associaton, State of Rio Grande do Sul – Orofacial Pain Diploma Program

⁴Federal University of Rio Grande do Sul – UFRGS, Brazil

⁵Faculty of Medicine, Caxias do Sul University, UCS, Brazil 

Address Correspondence to:

Dr. Márcio L. Grossi

PUCRS Dental School

Avenida Ipiranga 6681

Porto Alegre, RS, Brazil

CEP  90619-900

Tel: (51) 3320-3562

Fax: (51) 3320-3626

E-mail: mlgrossi@pucrs.br

Abstract  

Approximately 6 to 16% of patients with trigeminal neuralgia symptoms present intracranial tumors, the most common being acoustic neuroma. Due to nerve compression in the area of the auditory canal, some symptoms reported by patients include hearing loss, tinnitus, headaches, vertigo and trigeminal disturbances and may also provoke an increased muscle response in the surrounding head and neck musculature, which may mimick signs and symptoms of temporomandibular disorders. In these cases, magnetic resonance imaging (MRI) has proved to be a useful tool in the differential diagnosis. The differential diagnosis between myofascial pain and neuralgic pain is important, as both classes of pains may present similar characteristics, although being of different origins. While the demand for special treatment increases, the purpose of this case report was to demonstrate the relationship between trigeminal neuralgia symptoms, intracranial tumors and temporomandibular disorders.  

Key words: temporomandibular disorders, temporomandibular joint, chronic pain, orofacial pain, acoustic neuroma, vestibular schwannom

 Introduction  

The term acoustic neuroma defines a benign tumor of the Schwann cell neurilemma, which grows mostly in the lower vestibular nerve of the 8^th cranial nerve.¹ From 1991 on, Vestibular Schwannoma (VS) became the most appropriate term, representing the real situation for the majority of cases. Schwannomas of the 8^th nerve are among the most commonly diagnosed tumor and account for approximately 6% of all brain tumors.²

            Tumors of the 8^th nerve are characterized by the slow progression of hearing loss, with or without loss of balance. This happens because these tumors grow slowly, causing such a gradual decrease in labyrinth stimulation that the central compensation mechanisms are able to reduce the impact of these symptoms.³ On the other hand, 5^th nerve tumors are characterized by pain and facial numbness. This pain frequently resembles trigeminal neuralgia.^2,4 In acoustic neuromas, although the facial nerve is anatomically impaired by the tumor growing adjacent to it, seldomly facial paralysis does appear in clinical cases, which is a sign of the remarkable resistance to compression exhibited by the 7^th nerve.⁵

            The afferent root of the trigeminal nerve, which links the Gasserian Ganglion to the pons, may be a site for neuroma, with the tumor growing in the cerebellopontine angle.^1,2,5 The majority of tumors growing in this region is comprised by neuromas of the acoustic nerve or schwannomas. At times, the trigeminal nerve can be partly affected by schwannomas, as the latter occurs adjacent to the former.

            Acoustic neuromas may be classified as small, medium or large. Small neuromas are characterized by appearing only in the pons. The pons comprises the nerves responsible for auditory performance, equilibrium and movements of motor muscles as well as some vessels of the inner ear. The medium-sized neuroma stretches from the pons to the cranial cavity, yet without compressing any brain structure. On the other hand, the large neuroma stretches outside the internal canal towards the cranial cavity and is large enough to produce some pressure on the brain, and thus to alter important vital centers.⁶

            Trigeminal neuralgia is a symptom that may be present in acoustic neuroma cases.⁷ It was described by the International Association for the Study of Pain (2004) as a ‘unilateral facial pain, resembling an electric discharge, limited to one or more branches of the trigeminal nerve path’.⁸ The pain is triggered by ordinary sensorial stimuli such as washing the face, shaving, applying make up, drinking water, speaking, brushing the teeth, among others.⁹ The pain lasts only a few seconds¹⁰, and the clinical diagnosis is based on the patient’s history.¹¹

            In a study using magnetic resonance imaging, Yang et al. observed that in 51 patients suffering from trigeminal neuralgia, 16% (8) presented acoustic neuroma.⁷ Similarly, Samii & Matthies reported that between approximately 1% and 3% of acoustic schwannoma patients presented trigeminal neuralgia symptoms.¹² Nevertheless, Selesnick et al. related that in a group of 126 patients with acoustic neuroma, none of them presented neuralgia.¹³

Prevalence

            Of every 100 temporal bones selected and submitted to post-mortem anatomy studies, one presented neuroma on the vestibular nerve. The prevalence of this disorder, considering the current diagnosis conditions, is 8 in 1,000,000 subjects. Neuroma occurs slightly more often in women (55%). It happens independently of ethnicity and is more frequently diagnosed in men within the 50-60 year old age group (61%).¹ It is estimated that between 2,000 and 3,000 new unilateral vestibular neuroma cases are diagnosed yearly (incidence) in the US, which characterizes a 1:100,000 occurrence.¹⁴ Research has shown that unilateral neuroma is not hereditary, and only one case in 1,000 cases occurred in which mother and daughter suffered form the disorder.¹

 Pathology (Microscopical Findings)

            As a rule, two kinds of microscopical findings can be observed according to the description elaborated by Antoni in 1920. First, acoustic neuroma of Type A is defined by a more closely packed tissue in which cells form a palisade pattern, in a bipolar, parallel cell arrangements, disposed in interlacing bundles that alternate with enucleate fibrilar zones composed of cellular processes. Elongated nuclei occur typically.^1,15 Second, type B occurs as a more loosely organized tissue, of a more noticeable reticulated appearance and interstitial edema.¹ Neoplastic cells having condensed nuclei and indistinguishable cytoplasm are observed, and at first sight, may look like lymphocytes.¹⁵ 

 Diagnosis and Prognosis 

            The vestibular signs, the effect on the trigeminal nerve, and the cerebellar and intracranial pressure signs may all become noticeable with tumor growth, thus enabling the delineation of a sequential and evolutionary pattern.¹ The clinical signs may be characterized as: a) progressive unilateral or asymmetrical neuro-sensory dysacusis, b) intermittent hearing loss, c) tinnitus and sensation of fullness in the ear, d) lasting positional vertigo, e) difficulties in walking, f) visual blurring, g) trigeminal neuralgia, and e) headaches.^{1,11,16,17,18} Hearing ability is normal in at least 8% of cases, and tumor is suspected in the case of unusual or bizarre complaints that are investigated by MRI.¹

            Matsuka et al. listed the following symptoms related to acoustic neuroma: hearing deficits (60 to 97%), tinnitus (50 to 66%), vestibular disturbances (46 to 59%), numbness or tingling of the face (33%), headaches (19 to 29%), dizziness (23%), Bell’s palsy (17%), and trigeminal disturbances – hypesthesia, paresthesia, and neuralgia (12 to 45%).¹⁸

            Differential diagnosis between acoustic and trigeminal neuromas is fundamentally based on early impairment of auditory acuity ispilateral to the lesion in patients with 8^th nerve neuroma.^1,2,5 The use of imaging techniques is also necessary to diagnose the tumor. MRI is more advantageous than any other imaging technique, including CT scans, when identifying lesions in the trigeminal nerve path, and it is considered the technique of choice in the diagnosis of acoustic neuromas.¹⁹ Although the schwannoma is benign, morbidity is high because of the growing in the vestible as well as to the compression of vital structures such as the cranial nerves and the brain.¹⁴ 

Case report

            A 59-year-old woman was referred to the Center for Post Graduation Studies on Pain and Temporomandibular Disorders (TMD) of the Brazilian Dental Association in the State of Rio Grande do Sul (ABO-RS), Brazil, with acute pains around the lower lip, jaw, and right temporomandibular joint (TMJ), which impaired mouth opening. The main complaint was the difficulty to open the mouth due to shooting pain attacks on the right side of the face. Pain happened along the trigeminal nerve path, yet not reaching beyond the median line. Pain attacks were typically sudden, acute, short and episodic. The patient’s previous history, assessed by the HAD questionnaire (Hospital Anxiety and Depression Scale), revealed the clinical signs characteristic of depression and anxiety. These pains were characterized by persistent and localized episodes of bilateral pain in the left and right masseter as well as temporalis muscles that increased with function, and the presence of painful hypertrophic bands. When palpating the right masseter, pains were felt in the insertion region and in the muscle itself and were graded as 3 by the patient on a four-point scale. On the left side, pains happened in the masseter itself and were graded as 1. As for right and left temporal muscles, the patient reported grade 1 pains in all muscle sheaths. Pterygoid muscles were also reported to be affected by the pain on both sides, graded as 3.

            A visual scale was used to measure pain. The patient characterized facial pain episodes as grade 10, while muscle pains were graded as grade 7. These pains were of graded as 8 on average for the past 6 months. The patient’s everyday chores as well as professional work was impaired by the pain, which also affected her social and family life. Furthermore, the patient exhibited clicking and popping sounds in both TMJs and reported displaced bite, a history of mandible locking, both at day and night, teeth grinding, and a certain degree of discomfort in the morning.

The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) was used to assess the patient’s physical characteristics. On the first occasion, this test was not completed, because of the very small mouth opening (26 mm). The patient was instructed to make use of moist heat on the affected muscle area for 20 min, 3 times a day, for fourteen days. A non-steroid anti-inflammatory drug selective cyclo-oxygenase 2 was prescribed, three times a day, for the same period.²⁰

On a second occasion, the RDC/TMD questionnaire was again applied to the patient. Mouth opening was 36 mm, painless and with no need for intervention. The patient was able to further open the mouth 44 mm with assistance and then with intense pain. An overbite of 3 mm was observed, along with a lateral centric slide of 2 mm to the left of the median line. The opening pattern was S-shaped, deviated to the right side, presenting a 4-mm maximum lateral excursive movement to the right and 12 mm to the left.  Regarding articular sounds, a click was observed on the right side, at 23 mm opening, and on the left, at 25 mm. On closing, clicking was heard at 21 mm on the right and 25 mm on the left. Reciprocal sounds ceased in protrusive movement on both sides, but they were present in lateral movements.

            The MRI revealed a slight disk displacement, with a decrease on the right side and an extensive tumoral lesion in the right acoustic channel stretching to cerebellopontine angle (Figure 1a), suggesting a schwannoma of the eight acoustic nerve.

            Initially, the treatment proposed was to reduce localized muscle pain using anti-inflammatory drugs, muscle relaxation drugs, and moist heat in the affected muscular region, for four days. Concomitantly, a Michigan-type bite plane was manufactured to stabilize occlusion and to rule out dental influence as a trigger to central pain, to decrease abnormal muscle activity, as well as to diminish muscle pain sensitivity. In the follow-up period, the splint underwent adjustments, and from that moment on, the patient started using the splint both at day and night, removing it only to eat and clean her teeth. With the sequence of adjustments and frequent control, the patient reached a favorable response to the use of the splint, improving the pain prospects.

            The patient was referred to a psychiatrist for a more comprehensive evaluation of her psychological condition, which revealed symptoms that were suggestive of anxiety and depression. Similarly, the patient was advised to see a brain surgeon to assess the tumoral lesion (figures 1b and 1c) and to investigate dizziness, vertigo and neuralgia. After medical assessment, the patient began to take sertraline, carbamazepine and clonazepam, with subsequent decrease in pain crisis.

Figures 1a, 1b, 1c. Frontal, saggital and horizontal view of an acoustic neuroma (vestibular schwannoma) of the eight cranial nerve in the internal auditory canal.

 Discussion and Final Remarks 

            As a rule, acoustic neuromas grow slowly.¹⁸ In the present study, MRI showed that there was a 0.5 cm growth in 8 months. Due to this slow growth and to the neurologic adaptations undergone by patients, clinical symptoms are concealed and at times only superficially observed and investigated.^13,21,22

            Facial pain caused by tumors is often related to neurologic abnormalities such as: a) sensory changes, b) loss of reflexes, and c) constant pain. Nevertheless, these neurologic symptoms may be misdiagnosed or wrongly interpreted in some cases.²³ Patients place little value on these symptoms, since they are not very intense and non-debilitating and ignore the need for more specific treatment. According to Matsuka et al., patients take between 0.6 and 5 years to look for medical care. Similarly, the case study presented here revealed that the patient had felt myofascial pain as early as at 8 years of age.¹⁸

            Regarding differential diagnosis, some of the symptoms described in the literature, which are associated with the internal auditory canal, are otovestibular dysfunctions, such as hearing loss, tinnitus, vertigo and dizziness.²⁴ In the present case report, such symptoms were occasionally reported. According to Fricton et al. (1985), in a review of 164 subjects, patients with temporomandibular disorders may also describe similar otologic and neurologic symptoms.²⁵ For example, 42.1% of TMD patients presented with tinnitus, 41.5% with perceived ear pain, 23.1% with vertigo, and 17.7% with perceived hearing loss. In addition, 27.4% of the subjects presented with tingling, 26.2% with numbness, 14% with blurred vision, 12.2% with twitching, 7.9% with tremors, and 7.3% with lacrimation. These symptoms might be explained by peripheral and central sensitization due to ongoing inflammatory process in the masticatory muscles and/or temporomandibular joint or may be in fact medical conditions with associated and reflex muscular and skeletal symptoms, similar to TMD.²⁶ At the present time, medical imaging, particularly MRI, as well as a thorough multidisciplinary assessment, are probably the greatest tools in differentiating the two possible sources of pain as well as otologic and neurologic symptoms.

            Regarding treatment, the differential diagnosis described above is of utmost importance as well as a multidisciplinary team for chronic pain management. If TMD is suspected to be the major etiology after the negative confirmation of neoplasia (particularly acoustic neuroma), an interocclusal Michigan bite appliance may be sufficient to decrease all symptoms. Nevertheless, anticonvulsants are the drugs used at the begining of treatment to prevent and treat dizziness as well as in migraine prophylaxis. This class of drugs is also used in the management of chronic pain (neuropathies and neuralgias).²⁴ For trigeminal neuralgia, carbamazepine is the drug of first choice, controlling pain in 70-98% of cases; nevertheless, some patients present drug intolerance.^11,28

            Bullit et al. reported that carbamazepine is an efficient drug in the treatment of trigeminal neuralgia associated with intracranial tumors.¹⁰ Other studies have also proved the efficiency of other drugs, such as gabapentine in trigeminal neuralgia therapy.^29,30 The action of gabapentine has not been fully established and may involve the modulation of gama-aminobutiric acid and glutamate, or even have an effect on calcium channels.³⁰ With the prescription of such drugs, the patient reported a decrease in occurrences and duration of crises. Still, Yang et al. reported an increase in the number of patients suffering from trigreminal neuralgia associated with intracranial tumors that resisted the treatment with these drugs.⁷

            Other drugs may be useful in the control of neuralgic pain drugs, such as baclofen, lamotrigine and tricyclic antidepressants. In the case presented here, the pain attacks have been controlled by the patient, but crises still persisted due to the delay in undergoing surgery. Tumors that involve the trigeminal nerve are uncommon, but are important causes of trigeminal neuralgia and myofascial pain.¹⁰ Because of having similar characteristics, the concomitant occurrence of myofascial pain and neuropathic pain makes the diagnosis difficult. The differential diagnosis between these types of pains is necessary for their correct management. Myofascial pains that are localized, increase in intensity when the affected region is palpated, and occur with the presence of hypersensitive (taut) bands and trigger points. Neuropathic pains are generated in the central nervous system and may simulate a superficial somatic pain, similar to the myofascial pain, but they do not exacerbate during muscle palpation and not related to taut bands or trigger points.³¹  

            The treatment must be appropriate and specific to the different types of pain. The use of anti-inflammatory and central muscle relaxation drugs together with moist heat becomes effective in the control of somatic myofascial pain. The neuralgic pains must always be investigated in detail, as they bring about debilitation and also because such pains may at times come from intracranial tumors.¹⁰ The use of imaging in such cases becomes indispensable. The MRI is the most effective technique to detect intracranial structural lesions. It has advantages over CT as well as over any other type of imaging in the identification of soft tissues lesions, nerve paths and presence of tumors, as mentioned above.^19,32 The improved resolution for soft tissues and the capacity to visualize multi-layer sections contribute to a better assessment of intracranial anatomic segments of the trigeminal nerve.

            The prognosis of the acoustic neuroma surgery is good, although all surgical procedures are under a certain morbidity risk.^18,33 Hearing impairment in the affected side is a likely outcome as well as with a lesion in the trigeminal nerve. The literature review on the subject reveals that there might be a need for a clinical assessment when intracranial tumor is diagnosed, such as the acoustic neuroma, and when the patient initially reports unilateral hearing loss, apart from tinnitus. A clinical diagnosis must be carried out, together with an investigation if the patient’s history and imaging techniques like MRI.

   References 

1.     Costa SS, Cruz OLM: Otorrinolaringologia: princípios e práticas. Porto Alegre: Artes Médicas, 1994.

2.     Tierney Junior LM: Current Medical Diagnosis e Treatment. 43^th Ed. United States: Mc Graw Hill, 2004.

3.     Sagar SM, Israel MA: Tumores primários e metastáticos do sistema nervoso. In Braunwald E, Fauci AS, Kasper DL, Hauser SL, Longo DL, Jameson JL. Harrison – Principles of Internal Medicine, 15^th Ed. United States: Mc Graw Hill, 2001:2594-2604.

4.     Plum F, Posner JB: Intracranial neoplasms, CNS complications of cancer, and states of altered intracranial pressure. In Andreoli TE, Benett JC, Carpenter CCJ, Plum F. Cecil Essentials of Medicine. 4^th Ed. Philadelphia: Saunders, 1997:888-897.

5.     Tolosa APM: Propedêutica Neurológica – Temas Essenciais. 2^nd Ed. São Paulo: Sarvier, 1971.

6.     Bento RF, Brito Neto RV, Sanchez TG. Complicações da Cirurgia do Schwannoma Vestibular. Arquivos da Fundação de Otorrinolaringologia 2001:5:206-207.

7.     Yang J, Simonson TM, Ruprecht A, Meng D, Vincent SD, Yuh WTC. Magnetic resonance imaging used to assess patients with trigeminal neuralgia. Oral Surg Oral Med Oral Pathol Oral Radio Oral Endod 1996:81:343-350.

8.     Headache Classification Subcommittee of the HIS. The International Classification of Headache Disorders Second Edition. Cephalalgia 2004:24:126-127.

9.     Olesen J. Classification and diagnostic criteria for headache disorders, cranial neuralgia, and facial pain. Cephalgia 1988:8:1-96.

10.    Bullitt E, Tew JM, Boyd J. Intracranial tumors in patiens with facial pain. J Neurosurg 1986:64:865-871.

11.    Wood, S. Aetiology, signs, symptoms and treatment of trigeminal neuralgia. Nursing Times 2004:100:36-39.

13.    Selesnick SH, Jackler RK, Lawrence WP. The changing clinical presentation of acoustic tumors in the MRI era. Laryngoscope 1993:103:431-436.

14.    National Institutes of Health. Consensus Development Conference Statement. Acoustic Neuroma. 1991:9:1-24.

15.    Burger P, Scheithaver B: Atlas of Tumor Pathology – Tumors of the Central System Nervous. 3rd Ed. Washington: AFIP, 1994.

16.    Erickson LS, Sorenson GD, McGavran MH. A Review of 140 Acoustic Neurinomas (Neurilemmoma). Laryngoscope, 1965:75:601-627.

17.    Mathew GD, Facer Gw, Suh KW, Houser OW, O’Brien PC. Symptoms, findings, and methods of diagnosis in patients with acoustic neurinoma. Laryngoscope 1978:88:1893-1903.

18.    Matsuka Y, Fort E, Merrill R. Trigeminal neuralgia due to an acoustic neurinoma in cerebellopontine angle. J Orofacial Pain 2000:14:147-151.

19.    Goh BT, Poon CY, Peck RHL. The importance of routine magnetic resonance imaging in trigeminal neuralgia diagnosis. Oral Surg Oral Med Oral Pathol Oral Radio Oral Endod 2001:92:424-429.

20.    Dworkin SF, LeResche L, eds. Research Diagnostic Criteria for Temporomandibular Disorders. J Craniomandibular Disord Facial Oral Pain 1992; 6(4):301-355.

21.    Manni A, Brunori P, Giuliani M, Modoni M, Bizzi G. I sintomi otovestilolari nei pazienti con disfunzione temporomandibolare – Studio elettromiografico. Minerva Stomatol 1996:45:1-7.

22.    Elias KMI. Neurinoma do acústico e disfunção temporomandibular: a importância do diagnótico diferencial. JBA 2004:4:20-23.

23.    Siqueira SRDT, Nóbrega JCM, Valle LBS, Teixeira MJ, Siqueira JTT. Idiopathic trigeminal neuralgia: Clinical aspects and dental procedures. Oral Surg Oral Med Oral Pathol Oral Radio Oral Endod 2004:98:311-315.

24.    Cooper BC, Cooper DL. Recognizing otolaryngologic symptoms in patients with temporomandibular disorders. J Craniomand Pract 1993:11:260-267.

25.    Fricton J, Kroening R, Haley D, Siegert R: Myofascial pain syndrome of the head and neck: a review of clinical characteristics of 164 patients. Oral Surg Oral Med Oral Pathol 1985;60:615-623.

26.    Sessle BJ. Mechanisms of Orofacial Pain in the Brain Stem. In: Orofacial Pain and Temporomandibular Disorders, Lippincott – Raven Publishers, Livraria Santos Editora Ltda. (Portuguese Translation), p.43-60, 2003

27.    Pharm LR, Pettengil CA. The use of anticonvulsants in orofacial pain. Oral Surg Oral Med Oral Pathol Oral Radio Oral Endod 2001:91:2-7

28.    Sato J, Saitoh T, Notani K, Fukuda H, Kaneyama K, Segami N. Diagnostic significance of carbamazepine and trigger zones in trigeminal neuralgia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2004:97:18-22.

29.    Sist T, Filadora V, Miner M, Lema M. Gabapentin for idiopathic trigeminal neuralgia: Report of two cases. Neurology 1997:48:1467.

30.    Carranza EJ, Schachter SC. Alternative uses of lamotrigine and gabapentin in the treatment of trigeminal neuralgia. Neurology 1998:50:1192.

31.    Okeson, JP. Tratamento das desordens temporomandibulares e oclusão. 4 Ed., São Paulo: Artes Médicas, 2000.

32.    Lye RH, Ramsden RT, Stack JP, Gillespie JE. Trigeminal nerve tumor: Comparison of CT and MRI. Case report. J Neurosurg 1987:67:124-127.

33.    McCormick PC, Bello JA, Post KD. Trigeminal Schwannoma: Surgical series of 14 cases with review of the literature. J Neurosurg 1988:69:850-860.

Send mail to neuroone@aol.com with questions or comments about this web site.
Copyright © 2001 Preferred Provider Care
Last modified: 03/26/04