The Laryngoscope Lippincott Williams & Wilkins, Inc. © 2005 The American Laryngological, Rhinological and Otological Society, Inc.
Successful Treatment of a Postpolio Tinnitus with Type A Botulinum Toxin Paolo Scolozzi, MD, DMD; Emmanuel Carrera, MD; Bertrand Jaques, MD, DMD; Thierry Kuntzer, MD
Objectives/Hypothesis: Objective tinnitus is a symptom often observed in patients with chronic hyperactivity of masticatory muscles. Methods: We report here the unusual case of a 63-year-old woman who developed a distressing tinnitus related to contractions of reinnervated masticatory muscles. This reinnervation process was caused by a postpolio syndrome that gave rise to an acoustic resonance phenomenon transmitted to the middle ear as an audible sound. Results: The tinnitus was successfully treated with electromyography-guided intramuscular injections of type A botulinum toxin. Conclusion: The intramuscular injection of botulinum toxin was found to be effective in relieving severe and disabling postpolio tinnitus. Key Words: Tinnitus, myofacial pain dysfunction, botulinum toxin, postpolio syndrome. Laryngoscope, 115:1288 –1290, 2005
INTRODUCTION Tinnitus is defined as the perception of sound in the ears or head where no external source is present and is a common symptom in the general population, with a prevalence varying from 2% to 44%.1,2 Tinnitus may be either subjective or objective. Subjective tinnitus is heard only by the patient, whereas objective tinnitus is heard by the examiner as well. Objective tinnitus has also been reported in many patients with temporomandibular disorders (TMD), especially those presenting a chronic myofacial pain and dysfunction syndrome.1,3 Myofacial pain dysfunction (MPD) is a common cause of chronic facial pain, headache, and limited masticatory function, which results from the chronic hyperactivity of the masticatory muscles usually seen during bruxism, but all neurologic or muscular diseases can potentially cause such a syndrome.4
From the Department of Otolaryngology/Head and Neck Surgery, Division of Oral and Maxillofacial Surgery (P.S., B.J.), and the Department of Neurology (E.C., T.K.), Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. Editor’s Note: This Manuscript was accepted for publication March 29, 2005. Send Correspondence to Dr. Paolo Scolozzi, Department of Otolaryngology/Head and Neck Surgery, Division of Oral and Maxillofacial Surgery, Centre Hospitalier Universitaire Vaudois, 1011 Lausanne, Switzerland. E-mail:
[email protected] DOI: 10.1097/01.MLG.0000165371.98079.BD
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We present here the unusual case of a patient who complained of a disabling tinnitus of 3 years duration related to an abnormal resonance of the masticatory muscles that revealed an unknown bulbar postpolio syndrome. The tinnitus was successfully treated by electromyography (EMG)-guided intramuscular injections of type A botulinum toxin.
CASE REPORTS In September 2000, a 63-year-old woman noticed for the first time a left nonpulsatile tinnitus that she described as a continuous “motor-like noise,” like a “mower,” without vertigo, otorrhea, or hypoacusia. Her medical history was relevant for an unknown, severe illness at the age of 5 years with a consequent weakness of the masticatory and facial muscles. At the age of 18 years, she underwent a condyloplasty of both mandibular condyles because of osteoarthritis. The otolaryngologic examination, the evoked auditory brainstem responses, and brain magnetic resonance imaging were normal, as were the standard blood tests, including Lyme disease serology. Given the absence of any identifiable etiology of the tinnitus, it had been explained to the patient that in such cases, the purpose of treatment was based on treating the patient’s emotional reaction to tinnitus rather than the tinnitus itself, using psychotherapeutic measures such as cognitive therapy.3 The patient had thus been followed in psychotherapy for 2 years. At the beginning of this therapy, she noticed an improvement, with the persistence of a slight residual tinnitus. In December 2001, the situation worsened again with an exacerbation of the intensity and frequency of her left tinnitus and with the appearance of a new tinnitus on the right side and bilateral temporomandibular pain. The tinnitus was permanent and prevented her from sleep and rest, to the point where she expressed suicidal thoughts. The otolaryngologic examination that followed this change in symptoms was once again normal, and she was referred to a maxillofacial surgeon for investigation and a diagnosis of a myofacial pain disorder syndrome was made, as well as a malocclusion. Occlusal equilibration and physical therapy, with muscle massage and stretching, together with relaxation exercises, were then started with a significant but transient improvement of the tinnitus over a period of a few weeks. In September 2003, the patient was referred to the neurologic department for investigation of masseter muscle fasciculations. The neurologic examination showed a bilateral atrophy as well as fasciculations and weakness of the masseter, temporal, and lateral pterygoideus muscles. A continuous, repetitive, low-tone bruit was heard with the stethoscope over both masseter muscles, and the bruit in-
Scolozzi et al.: Treatment of a Postpolio Tinnitus
creased with mouth closing. No motor weakness was found in the sternocleidomastoid, trapezius, or muscles of the upper or lower limbs, and the rest of the examination was normal. EMG was accomplished by intraoral insertion into the lateral pterygoideus muscle and extraoral insertion into the masseter muscle of needle recording electrodes to study changes in motor unit potentials (MUPs). At rest, EMG showed fasciculation potentials. During voluntary contractions, MUPs were reduced and were of long duration and high amplitude (up to 8 mV, normal ⬍ 3 mV) (Fig. 1A). No abnormal potentials were seen at rest in the pectoral muscles or in the proximal and distal upper limb muscles; however, high-amplitude MUPs were recorded in these muscles during voluntary contractions (Fig. 1B). These EMG features were characteristic of chronic denervation and reinnervation process. The sound produced by the masseter and lateral pterygoideus muscles’ contractions, recorded and transmitted by the loudspeakers, was identified by the patient as being her tinnitus’ noise. Indeed, there was a clear correlation between the highamplitude and long-duration MUPs with mouth closing (Fig. 2). The contraction threshold of these abnormal, reinnervated MUPs was abnormally low, and the final diagnosis of postpolio syndrome was thus retained. The patient was then referred to the maxillofacial unit for intramuscular injections of both masseter muscles with botulinum toxin type A. In October 2003, both left masseter and lateral pterygoideus muscles were injected with 25 U each of botulinum toxin type A (Botox; Allergan, Irvine, CA), which represented the half of the standard dose generally used for these muscles.5,6 The injections were percutaneous for the masseter muscle and intraorally for the lateral pterygoideus muscle. The tinnitus partially disappeared within a few days, and the noise was no longer audible by way of a stethoscope. No side effect was observed. The posttreatment EMG showed cessation of MPUs firing in the left masseter and lateral pterygoideus muscles. The severity of the tinnitus was assessed before and after the treatment on the basis of a visual analogue scale (VAS), in which 0 was no tinnitus, and 10 the worst tinnitus the patient ever had. In our patient, the preinjection VAS was 10 and after injection of Botox 3. The effect lasted 6 months, after which the VAS progressively raised to 6. The follow-up period is now 15 months, and the patient is satisfied with her actual situation, although her VAS is 6, and she refuses new injections of Botox.
Fig. 1. (A) Electromyographic recording during slight voluntary contraction of the left masseter muscle, demonstrating the reduced pattern of the trace and the high-amplitude motor unit potentials, indicative of a chronic reinnervation process. During interference pattern analysis of the electromyography traces in the biceps brachialis (B) and first interosseus muscles (C), the turns/amplitude analysis revealed normal turns but high amplitudes, again confirming a chronic reinnervation process.
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Fig. 2. Continuous firing of the motor unit potentials (MUPs) in the left masseter muscle. The sound of the loudspeaker was recognized by the patient as the sound of her tinnitus, and indeed there was a correlation between the recording of these high amplitude MUPs and cessation of the tinnitus when there were no MUPs firing (*). The threshold of the MUPs’ firing was abnormally low, and a cessation of firing could only be obtained by an active opening of the mouth.
DISCUSSION The relationship between MPD and tinnitus is widely recognized, but the pathogenesis is still obscure and speculative.1,3 Several reports have shown that patients with such an unusual association can improve by means of physiotherapy and behavioral psychologic therapy.1,3 In the present case, the MPD was related to a bulbar postpolio syndrome, which manifested with a predominant involvement of the muscles that close and protract the jaws. The following criteria—first described by Mulder et al.7 in 1972 for the diagnosis of postpolio syndrome—were all fulfilled: a prior episode of poliomyelitis with residual motor neuron loss, a period of neurologic and functional stability after recovery from the acute illness, a gradual onset of new weakness, abnormal muscle fatigue or muscle atrophy, and exclusion of other conditions that could cause similar manifestations. Bulbar postpolio syndrome has been more frequently described after an acute poliomyelitis with limb involvement rather than with bulbar involvement, probably because most patients with an acute bulbar involvement did not survive because of respiratory and swallowing difficulties.8 Bulbar muscle dysfunction was usually described as causing dysphagia,9 respiratory failure,8 or sleep disorders,10 whereas involvement of the masticatory muscles as a heralding manifestation of the syndrome has never been reported in the literature, to our best knowledge. In the present case, objective tinnitus was intimately related to the contraction of the masticatory muscles, which gave rise to an acoustic resonance phenomenon that was transmitted to the middle ear as an audible sound wave. This phenomenon probably arose from the neurogenic recruitment with larger than normal motor units, which were spread out over a greatly enlarged territory within the reinnervated muscles. Botulinum toxin A has been successful in treating several diseases with increased muscle tone, such as hemifacial spasms, cervical dystonia, spasmodic torticollis, oromandibular dystonia, palatal myoclonus, and strabismus.11 Recent studies have reported encouraging results also in treating TMD associated with chronic myofacial pain.3,6 The main inconvenience with this type of treatment is the reversibility of the pharmacologic efScolozzi et al.: Treatment of a Postpolio Tinnitus
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fect, which lasts approximately 3 to 4 months. Nevertheless, in the present case, the reduction of the tinnitus persisted beyond this time. This was also observed by other authors, although the underlying mechanism remains unknown.6,12 The other unpleasant side effect could have been the worsening of muscle weakness, which would have resulted in severe masticatory and eating difficulties. Fortunately, this did not occur in our patient, probably because the dose of Botox was adequately low.
CONCLUSION In our case, the intramuscular injection of botulinum toxin was found to be effective in relieving severe and disabling postpolio tinnitus. By analogy, injection of botulinum toxin may be equally effective in other conditions where reinnervation is the underlying mechanism in vibratory tinnitus. Nevertheless, we cannot rule out that the patient also benefited from a placebo effect. More cases have to be studied to better understand the role of the intramuscular Botox injections in the treatment of tinnitus related to hyperactivity of the masticatory muscles.
Acknowledgment We would like to thank Dr Bernard NATER (Lausanne-Switzerland) for having referred the patient.
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