Accepted Article
Article Type: Case Report
Acoustic neuroma manifesting as toothache and numbness
Raymond Lam
Corresponding Author: Raymond Lam General Dentist and Research Scholar International Research Collaborative- Oral health and equity Department of Anatomy, Physiology and Human Biology The University of Western Australia [email protected] +61409105235
Acknowledgements: The author would like to especially acknowledge John McGeachie for his invaluable advice and assistance in preparing this manuscript. The author also thanks Marc Tennant, Estie Kruger and the team at the International Research Collaborative – Oral Health and Equity, for their support.
The author thanks the patient in this report for agreeing to the publication of his case.
Running Title “acoustic neuroma in dental practice”
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/adj.12302 This article is protected by copyright. All rights reserved.
Accepted Article
ABSTRACT Acoustic Neuroma, also known as Vestibular Schwannoma, is a rare benign brainstem tumour involving the abnormal growth and proliferation of Schwann cells surrounding the vestibular division of the eighth cranial nerve. Although the most common symptoms are non-dentally related, there are instances where diagnosis of this potentially life threatening condition is triggered by an emergency presentation to the dentist for the most trivial of reasons. A 56 year old male presented to a dental clinic complaining of a toothache. Following history taking, examination and radiographs a carious lower right molar was extracted. The patient reported relief but later described post extraction numbness on the opposite side (left) of his lower jaw that could not be explained by anatomical principles or previous dental history. Further investigations revealed an acoustic neuroma as the underlying cause. This case highlights that not all signs and symptoms that occur in the mouth are abnormalities within the mouth. In particular, this case underscores the importance of recognizing that the spontaneous onset of certain symptoms may be due to significant non-dental pathology. Any numbness over the distribution of the trigeminal nerve must be investigated. The importance of the basic sciences and referring will also be emphasised.
Key Words: Acoustic Neuroma, neurological complications, toothache INTRODUCTION Acoustic Neuroma (AN) is a rare benign brainstem tumour involving the abnormal growth and proliferation of Schwann cells. Unabated growth can compress cranial nerves V to XII. This area is rich in nerves, their sensory tracts on the lateral side of the medulla and vascular structures (vertebral, basilar arteries and their important This article is protected by copyright. All rights reserved.
Accepted Article
branches) around the brain stem (Figure 1)1. Compression of these structures may result in a series of complications with the most common symptoms being tinnitus, hearing loss and imbalance1. Despite this, these tumours can also present with other symptoms.
This case report describes how a common complaint resulting in a visit to the dentist resulted in the detection of an acoustic neuroma. A patient with a toothache sought treatment in a dental clinic as an emergency visit. The source of the pain was located, and the offending tooth extracted. Shortly after reporting relief from his presenting complaint, the patient reported unusual patterns of altered sensation that could not be explained by anatomical principles or previous dental history. In presenting this case report, an appreciation of the basic sciences as well as the importance of multi-disciplinary management will be emphasised. Whilst a complete account is documented, the focus is on aspects that are important to the general dentist rather than on the surgical aspects involved with neurosurgery.
CASE REPORT A 56 year old male with a history of well controlled type II diabetes mellitus and hypertension presented to the dental clinic complaining of a toothache. Following history taking, examination and radiographs (Figure 2) a carious and unrestorable lower right molar (47) was extracted under an inferior alveolar nerve block. The extraction was uncomplicated. The dentist contacted the patient by telephone a few days later and his presenting pain had subsided.
This article is protected by copyright. All rights reserved.
Accepted Article
Three weeks later the patient reported numbness on the tongue and lip which caused difficulty with eating. He was advised to return to the clinic for a review examination. The findings at this appointment were most unusual.
Two inconsistent findings in relation to the recent extraction and numbness prompted the dentist to consider alternative diagnoses. Firstly, as the peri-apical radiograph demonstrated that the apex of the tooth was beyond the inferior alveolar canal, its extraction was excluded as the cause of the numbness. Secondly, the numbness on the lip and tongue was always on the opposite side of the extracted tooth.
The patient was questioned further about his history. He reported a previous burning sensation on the left side of the tongue not mentioned at the initial examination. The dentist initially thought this may be associated with the disturbance to his diabetic condition following the recent extraction. An OPG was taken for general assessment of the maxilla-mandibular region.
As the image did not provide further clues to
explain the symptoms with local causes excluded, the patient was referred to an Oral Medicine specialist where the condition was jointly monitored and investigated.
The patient informed the dentist that the numbness had shifted over time. Using a periodontal probe and noting the patient’s response, the numbness (anaesthesia to reduced sensation) had shifted around the orofacial region but was always on the patient’s left side. He noted that it was difficult to chew, which was likely due to the reduced tonicity and sensation of his muscles of mastication that accompanied the
This article is protected by copyright. All rights reserved.
Accepted Article
paraesthesia. This was further compounded by the increased burning sensation on the tongue and the patient favouring his left side when eating due to the recent extraction. Cranial nerve tests were within clinical normal limits, apart from a 10 year history of tinnitus in the left ear. Minor reduced hearing was also noticed in the left ear.
An MRI was obtained and the cause of the paraesthesia located (Figure 3). The images revealed a large complex solid mass alongside the brain stem averaging 20mm in all dimensions.
The lesion was most likely an Acoustic Neuroma.
Displacement of the maxillary and mandibular divisions of the trigeminal nerve and widening of the auditory canal by the lesion had caused the unexplained numbness.
The patient was referred to a neurosurgeon and an ENT specialist where the lesion was surgically removed. The surgery resulted in an exacerbation in the loss of hearing and resulted in a drooping eye from facial palsy on the left side.
The
patient’s speech and chewing were affected as well as occasional dental discomfort consistent with trigeminal neuralgia. DISCUSSION Diagnostic Challenge This case highlights the diagnostic challenges that may be encountered in the dental clinic. Appreciating that nerve injuries may occur when teeth are extracted, it was unsurprising that this was the dentist’s provisional diagnosis. Renton et al (2012) reported that up to 70% of nerve injuries from extractions result in some form of
This article is protected by copyright. All rights reserved.
Accepted Article
neuropathic condition2. However, in the present case, it was the atypical location and character of the condition that raised suspicion.
Considering first principles, it was unlikely that damage to the mandibular branch of the trigeminal nerve would affect its contra-lateral side. Basic principles in neuroanatomy indicate clear divisions between the left and ride side with no evidence to demonstrate cross-over of nerve fibres.
Furthermore, as the peri-apical radiograph
excluded a local cause, namely nerve damage during extraction, there had to be another reason for the symptoms.
Since numbness over the patient’s face could not be explained by anatomical principles or previous dental history, a range of diagnoses were considered. Table 1 outlines a range of differential diagnoses, odontogenic and non-odontogenic, for the loss of sensation in the trigeminal region. After revisiting the history, and OPG was obtained for general assessment. As this did not provide any clues to explain the symptoms, further radiographic imaging was considered where a MRI subsequently revealed a tumour.
In relation to the initial toothache, this case represented two separate lesions presenting in a close temporal relationship. The patient presented with a toothache, received treatment and the pain resolved.
He subsequently presented with
neurological symptoms and referred for appropriate management. Stated differently, this case involved two mutually exclusive diagnoses with symptoms localised in the
This article is protected by copyright. All rights reserved.
Accepted Article
mouth. Any numbness over the distribution of the trigeminal nerve must be investigated until the source has been identified.
Acoustic Neuroma In this case, an MRI at the level of the internal auditory canal demonstrated an Acoustic Neuroma. These are rare CNS tumours with an incidence of 1:100,000 2. Although the patient exhibited the classic symptoms of AN, namely tinnitus and loss of hearing, he considered these symptoms unremarkable. These symptoms had only been diagnosed as part of his dental follow up. The patient stated that he only sought treatment because the toothache became unbearable. In this instance, the patient received surgery to remove the tumour under the management of a neurosurgeon and ENT specialist.
Post operative status As surgical access to this confined zone is difficult, there is a high likelihood of introducing new symptoms and/or exacerbating pre-existing conditions. Many of these symptoms can be related to the nerves affected by the tumour (Figure 1)1. Damage to the facial nerve resulted in reduced tonicity in his muscles of facial expression, as well as affecting taste in the anterior two thirds of the tongue via the chorda tympani nerve. Similarly, compression of the hypoglossal nerve affects motor movement in this region of the tongue. Impingement of the maxillary and mandibular divisions of the trigeminal nerve caused neuralgic pain in the mid to lower face as well as affecting motor fibres that innervate the muscles of mastication. Due to
This article is protected by copyright. All rights reserved.
Accepted Article
encirclement of the vestibulocochlear nerve around the tumour, the patient suffered complete hearing loss on the left side and also affected his balance. The glossopharyngeal nerve that innervates the posterior tongue and pharynx resulted in swallowing difficulty (dysphagia), also contributing to speech difficulties. By appreciating anatomy, all potential complications following surgery can be predicted and explained to the patient.
CONCLUSION An acoustic neuroma is a benign brainstem tumour that can manifest as a toothache and/or numbness around the oro-facial region. This case demonstrates that not all signs and symptoms that occur in the mouth are abnormalities within the mouth. It is important to recognize that the spontaneous onset of certain oral symptoms may be due to significant and more sinister non dental pathology. Although this may present as a diagnostic challenge in dental practice, any numbness over the distribution of the trigeminal nerve must be investigated. This underscores the importance of the basic sciences and knowing when to refer to specialists for multi-disciplinary management.
References 1. Hansen T. Netter’s Clinical Anatomy. 3rd Ed. Philadelphia:Saunders;2014. 2. Ho S, Kveton J. Acoustic neuroma. Assessment and management. Otolaryngol Clin North Am. 2002 Apr; 35(2):393-404, viii. 3. Renton T, Dawood A, Shah A, Searson L, Yilmaz Z. Post-implant neuropathy of the trigeminal nerve. A case series. British Dental Journal. 2012. DOI: 10.1038/sj.bdj.2012.497
This article is protected by copyright. All rights reserved.
Accepted Article
Differential Diagnosis for loss of sensation in trigeminal nerve • •
•
•
•
•
•
Developmental (eg. syringobulbia) Inflammatory o Mixed Connective tissue Disease (eg. scleroderma) o Autoimmune (eg. multiple sclerosis) o Metabolic (eg. diabetes mellitus) Infective o Viral (eg. Herpes zoster virus, herpes simplex) o Bacterial (eg. syphilis) Neoplastic o Intra-cranial compression (eg. acoustic neuroma, nasopharyngeal carcinoma) o Perineural spread (eg. adenoid cystic carcinoma) o Metastasis (eg. adenocarcinoma) Drug Induced o Local Analgesia (eg. block analgesia) o Prescription (eg. statins, anti-depressants, chemotherapeutics) Traumatic o Maxillary and Mandibular Fractures (eg. middle cranial fossa, Le Fort) o Iatrogenic (eg. implant placement, endodontics, third molar removal) Vascular o Cerebrovascular disease (eg. stroke, embolism)
Note: This table was composed by the author from various sources to indicate some common causes of loss of sensation with the Trigeminal Nerve.
This article is protected by copyright. All rights reserved.
Accepted Article This article is protected by copyright. All rights reserved.
Accepted Article This article is protected by copyright. All rights reserved.
Article Type: Case Report
Acoustic neuroma manifesting as toothache and numbness
Raymond Lam
Corresponding Author: Raymond Lam General Dentist and Research Scholar International Research Collaborative- Oral health and equity Department of Anatomy, Physiology and Human Biology The University of Western Australia [email protected] +61409105235
Acknowledgements: The author would like to especially acknowledge John McGeachie for his invaluable advice and assistance in preparing this manuscript. The author also thanks Marc Tennant, Estie Kruger and the team at the International Research Collaborative – Oral Health and Equity, for their support.
The author thanks the patient in this report for agreeing to the publication of his case.
Running Title “acoustic neuroma in dental practice”
This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10.1111/adj.12302 This article is protected by copyright. All rights reserved.
Accepted Article
ABSTRACT Acoustic Neuroma, also known as Vestibular Schwannoma, is a rare benign brainstem tumour involving the abnormal growth and proliferation of Schwann cells surrounding the vestibular division of the eighth cranial nerve. Although the most common symptoms are non-dentally related, there are instances where diagnosis of this potentially life threatening condition is triggered by an emergency presentation to the dentist for the most trivial of reasons. A 56 year old male presented to a dental clinic complaining of a toothache. Following history taking, examination and radiographs a carious lower right molar was extracted. The patient reported relief but later described post extraction numbness on the opposite side (left) of his lower jaw that could not be explained by anatomical principles or previous dental history. Further investigations revealed an acoustic neuroma as the underlying cause. This case highlights that not all signs and symptoms that occur in the mouth are abnormalities within the mouth. In particular, this case underscores the importance of recognizing that the spontaneous onset of certain symptoms may be due to significant non-dental pathology. Any numbness over the distribution of the trigeminal nerve must be investigated. The importance of the basic sciences and referring will also be emphasised.
Key Words: Acoustic Neuroma, neurological complications, toothache INTRODUCTION Acoustic Neuroma (AN) is a rare benign brainstem tumour involving the abnormal growth and proliferation of Schwann cells. Unabated growth can compress cranial nerves V to XII. This area is rich in nerves, their sensory tracts on the lateral side of the medulla and vascular structures (vertebral, basilar arteries and their important This article is protected by copyright. All rights reserved.
Accepted Article
branches) around the brain stem (Figure 1)1. Compression of these structures may result in a series of complications with the most common symptoms being tinnitus, hearing loss and imbalance1. Despite this, these tumours can also present with other symptoms.
This case report describes how a common complaint resulting in a visit to the dentist resulted in the detection of an acoustic neuroma. A patient with a toothache sought treatment in a dental clinic as an emergency visit. The source of the pain was located, and the offending tooth extracted. Shortly after reporting relief from his presenting complaint, the patient reported unusual patterns of altered sensation that could not be explained by anatomical principles or previous dental history. In presenting this case report, an appreciation of the basic sciences as well as the importance of multi-disciplinary management will be emphasised. Whilst a complete account is documented, the focus is on aspects that are important to the general dentist rather than on the surgical aspects involved with neurosurgery.
CASE REPORT A 56 year old male with a history of well controlled type II diabetes mellitus and hypertension presented to the dental clinic complaining of a toothache. Following history taking, examination and radiographs (Figure 2) a carious and unrestorable lower right molar (47) was extracted under an inferior alveolar nerve block. The extraction was uncomplicated. The dentist contacted the patient by telephone a few days later and his presenting pain had subsided.
This article is protected by copyright. All rights reserved.
Accepted Article
Three weeks later the patient reported numbness on the tongue and lip which caused difficulty with eating. He was advised to return to the clinic for a review examination. The findings at this appointment were most unusual.
Two inconsistent findings in relation to the recent extraction and numbness prompted the dentist to consider alternative diagnoses. Firstly, as the peri-apical radiograph demonstrated that the apex of the tooth was beyond the inferior alveolar canal, its extraction was excluded as the cause of the numbness. Secondly, the numbness on the lip and tongue was always on the opposite side of the extracted tooth.
The patient was questioned further about his history. He reported a previous burning sensation on the left side of the tongue not mentioned at the initial examination. The dentist initially thought this may be associated with the disturbance to his diabetic condition following the recent extraction. An OPG was taken for general assessment of the maxilla-mandibular region.
As the image did not provide further clues to
explain the symptoms with local causes excluded, the patient was referred to an Oral Medicine specialist where the condition was jointly monitored and investigated.
The patient informed the dentist that the numbness had shifted over time. Using a periodontal probe and noting the patient’s response, the numbness (anaesthesia to reduced sensation) had shifted around the orofacial region but was always on the patient’s left side. He noted that it was difficult to chew, which was likely due to the reduced tonicity and sensation of his muscles of mastication that accompanied the
This article is protected by copyright. All rights reserved.
Accepted Article
paraesthesia. This was further compounded by the increased burning sensation on the tongue and the patient favouring his left side when eating due to the recent extraction. Cranial nerve tests were within clinical normal limits, apart from a 10 year history of tinnitus in the left ear. Minor reduced hearing was also noticed in the left ear.
An MRI was obtained and the cause of the paraesthesia located (Figure 3). The images revealed a large complex solid mass alongside the brain stem averaging 20mm in all dimensions.
The lesion was most likely an Acoustic Neuroma.
Displacement of the maxillary and mandibular divisions of the trigeminal nerve and widening of the auditory canal by the lesion had caused the unexplained numbness.
The patient was referred to a neurosurgeon and an ENT specialist where the lesion was surgically removed. The surgery resulted in an exacerbation in the loss of hearing and resulted in a drooping eye from facial palsy on the left side.
The
patient’s speech and chewing were affected as well as occasional dental discomfort consistent with trigeminal neuralgia. DISCUSSION Diagnostic Challenge This case highlights the diagnostic challenges that may be encountered in the dental clinic. Appreciating that nerve injuries may occur when teeth are extracted, it was unsurprising that this was the dentist’s provisional diagnosis. Renton et al (2012) reported that up to 70% of nerve injuries from extractions result in some form of
This article is protected by copyright. All rights reserved.
Accepted Article
neuropathic condition2. However, in the present case, it was the atypical location and character of the condition that raised suspicion.
Considering first principles, it was unlikely that damage to the mandibular branch of the trigeminal nerve would affect its contra-lateral side. Basic principles in neuroanatomy indicate clear divisions between the left and ride side with no evidence to demonstrate cross-over of nerve fibres.
Furthermore, as the peri-apical radiograph
excluded a local cause, namely nerve damage during extraction, there had to be another reason for the symptoms.
Since numbness over the patient’s face could not be explained by anatomical principles or previous dental history, a range of diagnoses were considered. Table 1 outlines a range of differential diagnoses, odontogenic and non-odontogenic, for the loss of sensation in the trigeminal region. After revisiting the history, and OPG was obtained for general assessment. As this did not provide any clues to explain the symptoms, further radiographic imaging was considered where a MRI subsequently revealed a tumour.
In relation to the initial toothache, this case represented two separate lesions presenting in a close temporal relationship. The patient presented with a toothache, received treatment and the pain resolved.
He subsequently presented with
neurological symptoms and referred for appropriate management. Stated differently, this case involved two mutually exclusive diagnoses with symptoms localised in the
This article is protected by copyright. All rights reserved.
Accepted Article
mouth. Any numbness over the distribution of the trigeminal nerve must be investigated until the source has been identified.
Acoustic Neuroma In this case, an MRI at the level of the internal auditory canal demonstrated an Acoustic Neuroma. These are rare CNS tumours with an incidence of 1:100,000 2. Although the patient exhibited the classic symptoms of AN, namely tinnitus and loss of hearing, he considered these symptoms unremarkable. These symptoms had only been diagnosed as part of his dental follow up. The patient stated that he only sought treatment because the toothache became unbearable. In this instance, the patient received surgery to remove the tumour under the management of a neurosurgeon and ENT specialist.
Post operative status As surgical access to this confined zone is difficult, there is a high likelihood of introducing new symptoms and/or exacerbating pre-existing conditions. Many of these symptoms can be related to the nerves affected by the tumour (Figure 1)1. Damage to the facial nerve resulted in reduced tonicity in his muscles of facial expression, as well as affecting taste in the anterior two thirds of the tongue via the chorda tympani nerve. Similarly, compression of the hypoglossal nerve affects motor movement in this region of the tongue. Impingement of the maxillary and mandibular divisions of the trigeminal nerve caused neuralgic pain in the mid to lower face as well as affecting motor fibres that innervate the muscles of mastication. Due to
This article is protected by copyright. All rights reserved.
Accepted Article
encirclement of the vestibulocochlear nerve around the tumour, the patient suffered complete hearing loss on the left side and also affected his balance. The glossopharyngeal nerve that innervates the posterior tongue and pharynx resulted in swallowing difficulty (dysphagia), also contributing to speech difficulties. By appreciating anatomy, all potential complications following surgery can be predicted and explained to the patient.
CONCLUSION An acoustic neuroma is a benign brainstem tumour that can manifest as a toothache and/or numbness around the oro-facial region. This case demonstrates that not all signs and symptoms that occur in the mouth are abnormalities within the mouth. It is important to recognize that the spontaneous onset of certain oral symptoms may be due to significant and more sinister non dental pathology. Although this may present as a diagnostic challenge in dental practice, any numbness over the distribution of the trigeminal nerve must be investigated. This underscores the importance of the basic sciences and knowing when to refer to specialists for multi-disciplinary management.
References 1. Hansen T. Netter’s Clinical Anatomy. 3rd Ed. Philadelphia:Saunders;2014. 2. Ho S, Kveton J. Acoustic neuroma. Assessment and management. Otolaryngol Clin North Am. 2002 Apr; 35(2):393-404, viii. 3. Renton T, Dawood A, Shah A, Searson L, Yilmaz Z. Post-implant neuropathy of the trigeminal nerve. A case series. British Dental Journal. 2012. DOI: 10.1038/sj.bdj.2012.497
This article is protected by copyright. All rights reserved.
Accepted Article
Differential Diagnosis for loss of sensation in trigeminal nerve • •
•
•
•
•
•
Developmental (eg. syringobulbia) Inflammatory o Mixed Connective tissue Disease (eg. scleroderma) o Autoimmune (eg. multiple sclerosis) o Metabolic (eg. diabetes mellitus) Infective o Viral (eg. Herpes zoster virus, herpes simplex) o Bacterial (eg. syphilis) Neoplastic o Intra-cranial compression (eg. acoustic neuroma, nasopharyngeal carcinoma) o Perineural spread (eg. adenoid cystic carcinoma) o Metastasis (eg. adenocarcinoma) Drug Induced o Local Analgesia (eg. block analgesia) o Prescription (eg. statins, anti-depressants, chemotherapeutics) Traumatic o Maxillary and Mandibular Fractures (eg. middle cranial fossa, Le Fort) o Iatrogenic (eg. implant placement, endodontics, third molar removal) Vascular o Cerebrovascular disease (eg. stroke, embolism)
Note: This table was composed by the author from various sources to indicate some common causes of loss of sensation with the Trigeminal Nerve.
This article is protected by copyright. All rights reserved.
Accepted Article This article is protected by copyright. All rights reserved.
Accepted Article This article is protected by copyright. All rights reserved.
