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PRACTICE

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PRACTICE

  1. 1. IN BRIEF PRACTICE ● ● ● ● Neurological disorders may present in various ways including sensory disturbance, paralysis, altered level of consciousness, fits, speech disturbance, changes in muscle tone or bulk and tremor. Facial paralysis may be caused by stroke (upper motor neurone) or Bell’s Palsy (lower motor neurone). Surgery in the region of the facial nerve, particularly parotid surgery may also cause dysfunction of the nerve. Facial sensory loss (trigeminal nerve) may be caused by extracranial nerve injury. Other causes include multiple sclerosis, stroke and tumours. Patients with epilepsy may severely damage the oro-facial tissues in Grand Mal attacks. 4 A good history will alert the practitioner to those who are poorly controlled. ● Some of the drugs used for the treatment of neurological disorders impact on dental disease and VERIFIABLE its management. CPD PAPER ● In patients with severe or complex neurological disorders, consideration should be given to referring such patients for management in a hospital setting. General medicine and surgery for dental practitioners Part 4: Neurological disorders M. Greenwood1 and J. G. Meechan2 There are a number of neurological conditions that may be encountered in dental practice. It is important that a dental practitioner has a broad knowledge of the main neurological conditions since they may affect the provision of dental treatment. RELEVANT POINTS IN THE HISTORY factors should be asked about, and enquiry made GENERAL MEDICINE AND The patient may give a history of ‘blackouts’. It is about altered breathing, cyanosis or tongue bit- SURGERY FOR DENTAL important to be precise about what a patient ing during a fit. The latter is virtually a diagnos- PRACTITIONERS: means by this term as this can indicate anything tic feature of this type of epilepsy. Medication 1. Cardiovascular system from a loss of consciousness (LOC) to dizziness. taken and its efficacy should be assessed in terms When a history of blackouts is given, informa- of the degree of control achieved. Tonic-clonic 2. Respiratory system tion obtained from a witness might be useful. or Grand Mal epilepsy is classically preceded by 3. Gastrointestinal system The more that is known about the nature of such a warning or aura which may comprise an audi- 4. Neurological disorders an event, the better it can be anticipated and tory, olfactory or a visual hallucination. A loss of 5. Liver disease effectively managed (or prevented). consciousness follows leading to convulsions 6. The endocrine system The main points in the history are sum- and subsequent recovery. The patient may be 7. Renal disorders marised in Table 1. incontinent during a fit. The ‘tonic phase’ gives 8. Musculoskeletal system Syncope may be vaso-vagal in origin (the way to a ‘clonic phase’ in which there is repeti- 9. Haematology and simple faint) or may occur in response to certain tive jerky movements, increased salivation and patients with bleeding situations such as coughing. A vaso-vagal attack marked bruxism. After a fit of this type, a patient problems may be precipitated by the fear of dental treat- may sleep for up to 12 hours. If the fit continues 10. The paediatric patient ment, heat or a lack of food. It occurs due to a for more than 5 minutes or continues without a reflex bradycardia and peripheral vasodilation. proper end point, ‘status epilepticus’ is said to be Onset is not instantaneous and the patient will look pale, often feel sick and notice a ‘closing in’ Table 1 Main points in the history in the dental of visual fields. It cannot occur when a patient is patient with possible neurological disorders lying down and placing the patient flat with legs 1Lecturer, 2Senior Lecturer, Department of raised is the treatment. Jerking of limbs may • Blackouts, syncope Oral and Maxillofacial Surgery, The Dental occur. In carotid sinus syncope, hypersensitivity • Epilepsy School, Framlington Place, Newcastle of the carotid sinus may cause syncope to occur • Stroke, Transient Ischaemic Attack upon Tyne NE2 4BW Correspondence to: M. Greenwood on turning the head. Unlike vaso-vagal syncope • Multiple Sclerosis E-mail: beryl.leggatt@ncl.ac.uk this may happen in the supine position. • Facial pain Patients may suffer from epilepsy. If this • Parkinson’s Disease Refereed Paper presents as a blackout the most likely type is doi:10.1038/sj.bdj.4810275 • Motor Neurone Disease © British Dental Journal 2003; 195: Grand Mal. A description of the fit is useful as • Cranial Nerve problems (especially Bell’s Palsy) 19–25 this may enable early recognition. Precipitating BRITISH DENTAL JOURNAL VOLUME 195 NO. 1 JULY 12 2003 19
  2. 2. PRACTICE Table 2 Possible causes of loss of consciousness or ‘Blackout’ (on the opposite side to the cerebral lesion) and there may be a loss of speech or slurred speech Vaso-Vagal Syncope Simple faint when the CVA affects the left side of the brain. ‘Situational’ Syncope Cough TIA’s comprise a sudden onset of focal CNS Micturition signs or symptoms due to a temporary occlu- Carotid sinus hypersensitivity sion of part of the cerebral circulation. They are Epilepsy frequently associated with partial or complete Hypoglycaemia stenosis of the carotid artery system. The symp- Transient Ischaemic Attack toms resolve in less than 24 hours (usually Orthostatic Hypotension On standing from lying much more quickly). They are harbingers of a Signifies inadequate vasomotor CVA and the known patient will usually be tak- reflexes eg elderly patients on ing prophylactic aspirin. tablets to lower blood pressure Patients with Multiple Sclerosis have a ‘Drop attacks’ Sudden weakness of legs usually diverse condition comprising neurological signs resolved spontaneously and symptoms that are disseminated in both site Stokes-Adams Attacks Transient arrhythmia and time. A viral aetiology has been postulated Anxiety but the cause is not known. Onset is variable but Menieres Disease Vertigo, tinnitus, hearing loss optic neuritis can lead to visual disturbance or Choking blindness, which may be a presenting feature. Weakness or paralysis of a limb can occur. Nystagmus (jerky, oscillating movement of the present. This is an emergency situation which eyes — which can also be physiological) may requires urgent intervention with a benzodi- occur, as may ataxia (uncoordinated move- azepine eg intravenous diazepam. ments) and dysphagia. Loss of sphincter control Absence seizures or ‘Petit Mal’ tend to occur leading to urinary incontinence may occur. The in children who may suddenly arrest speech, diagnosis should be considered in a young attention and movement. So-called ‘partial’ patient presenting with trigeminal neuralgia or a seizures may be simple or complex. Simple facial palsy. Enquiry in such cases should be seizures consist of clonic movements of a group directed towards other areas to check for neuro- of muscles or a limb. Complex seizures may logical signs or symptoms elsewhere. involve hallucinations of hearing, sight or taste. Febrile convulsions are common in infancy FACIAL PAIN and do not predict progression to later epilepsy. Facial pain is common and may affect up to 50% Keeping the child cool with fans, paracetamol of the elderly population.1 A paroxysm of excru- and sponging with tepid water are the mainstays ciating stabbing pain lasting only seconds, in of treatment. the trigeminal nerve distribution suggests Stokes-Adams attacks describe losses of con- trigeminal neuralgia,2 particularly in patients sciousness occurring as a result of cardiac over 50 years of age. In the vast majority of arrhythmias. These may happen with the patient cases it is unilateral and most commonly affects Status epilepticus in any position and may occur with no warning the mandibular and maxillary divisions. Often a except for an awareness of palpitations. Recov- ‘trigger area’ may be identified from the history This is a medical ery is usually within seconds. Other potential that is stimulated by washing or shaving for causes of ‘blackouts’ are shown in Table 2. example. Talking may be enough to stimulate emergency and The patient may give a history of a stroke the pain. Usually the trigger is easily identified. practitioners should (Cerebrovascular Accident — CVA) or a so- Carbamazepine or phenytoin are the mainstays have a benzodia- called mini-stroke (Transient Ischaemic Attack of treatment. — TIA). A CVA may be haemorrhagic (sub- Other neurological causes of facial pain zepine in the arachnoid, cerebral), thrombotic or embolic in include post-herpetic neuralgia and atypical emergency drug origin. A subarachnoid haemorrhage results facial pain. In post-herpetic neuralgia the kit to treat this from rupture of a Berry aneurysm of the Circle patient complains of a burning pain (often in the of Willis (which lies at the base of the brain). ophthalmic division of the trigeminal nerve), condition Subarachnoid haemorrhages tend to affect a which may become chronic. There is no really younger age group than the other types of CVA successful treatment, transcutaneous nerve sec- and typically patients give a history of a sud- tioning and LA infiltration in the painful area den onset of excruciatingly severe headache. has been tried as has carbamazepine. Tricyclic The prognosis is poor, but has been improved antidepressants have also been used. by surgical and radiological obliteration of the When all other causes (including non-neuro- aneurysm. Hypertension and atherosclerosis logical causes of facial pain) have been exclud- are contributory factors to other types of CVA. ed, some patients may still complain of facial Cerebral thrombosis deprives the brain of part pain — usually unilateral. The pain is described of its blood supply and is the most common as severe, constant and not relieved by anal- type of stroke. Emboli leading to stroke can gesics. This type of pain is more common in arise on the wall of an atrium that is fibrillating young females and many are prescribed antide- or from the wall of a heart damaged after a pressants (although not always to curative myocardial infarction. Typical results of a CVA effect). Atypical facial pain is the term applied to are a sudden loss of consciousness, hemiplegia this type of facial pain. 20 BRITISH DENTAL JOURNAL VOLUME 195 NO. 1 JULY 12 2003
  3. 3. PRACTICE OTHER DISORDERS Table 3 Some possible causes of facial weakness Parkinson’s Disease results from degeneration of (mostly unilateral) the pigmented cells of the substantia nigra lead- Idiopathic Bell’s Palsy ing to dopamine deficiency. The incidence is Melkersson-Rosenthal Syndrome equal in males and females. The disease may also result from previous head injury or cerebrovas- Infection Ear infections cular disease. Clinically the patient may have TB tremor in the arms and hands (the latter being Ramsay Hunt Syndrome described as ‘pill-rolling’). A so-called ‘cog- Glandular Fever wheel’ type of rigidity may be seen on move- AIDS ment. Slow movements (bradykinesia) and rest- Trauma Facial lacerations/bruising lessness (akathisia) may also be noted. The in the region of the facial nerve patient may have an expressionless face and a Penetrating parotid injuries stooped posture. Impaired autonomic function Post-parotid surgery may lead to a postural drop in blood pressure and Neoplastic Primary or secondary cancers hypersalivation resulting in drooling of saliva. Neuroma of facial nerve Motor Neurone Disease comprises a group of Acoustic neuroma disorders that affect motor neurones at various Metabolic Diabetes Mellitus levels. There is no sensory loss and this helps dif- Pregnancy ferentiation from multiple sclerosis. The aetiolo- Sarcoidosis gy is unknown, but a viral agent is thought pos- Guillain-Barre Syndrome sible. Oral hygiene may be difficult in these patients and dysphagia and drooling may occur. Tumours may arise in various components of Looking for ‘forehead sparing’ is thus a way of the CNS and may be primary or metastatic, the differentiating between upper and lower motor latter being more common in the brain. Benign neurone causes of facial weakness. brain tumours are still a significant problem as Bilateral facial paralysis is rare. It may be they may cause pressure effects and may not be seen in sarcoidosis or the Guillain Barre Syn- amenable to surgery due to their site. Headaches drome (idiopathic polyneuritis) or posterior cra- are characteristically worse in the morning. nial fossa tumours. The rare Melkersson-Rosen- Tumours from which cerebral metastases arise thal Syndrome is a condition comprising tongue include lung, breast, GIT and kidney. fissuring, unilateral facial palsy and facial Impairment of vision may occur and this swelling. The lesions are histologically similar to may vary from mild disability to complete those of Crohn’s Disease. blindness. Diplopia or double vision may occur A summary of other cranial nerve lesions is after a ‘blowout’ fracture of the orbital floor3 given in Table 4. Nerves may be affected by a or injury to cranial nerves III, IV and VI. Tran- systemic cause eg diabetes mellitus, MS or sient visual disturbance may occur secondary there may be a local cause. Multiple cranial to local anaesthetic that has tracked to the nerve palsies may occur in Bulbar Palsy that inferior orbital fissure. comprises palsy of the tongue, muscles of Fig. 1 A patient with Bell’s Palsy. The ipsilateral forehead is affected also Myasthenia Gravis (MG) is an antibody- chewing/swallowing and facial muscles due to indicating a lower motor neurone mediated autoimmune disease with a deficiency loss of function of motor nuclei in the brain- lesion. Bell’s sign (see text) is also of functioning muscle acetylcholine receptors stem. The onset may be acute eg in infection demonstrated that leads to muscle weakness. The disorder such as polio, or may be chronic eg in tumours more commonly affects young women. The of the posterior cranial fossa. muscle weakness is progressive and develops Tics or involuntary facial movements may rapidly. Some cases are associated with the occasionally be seen in patients. These may be Eaton-Lambert Syndrome that may occur in habitual, particularly in children or may be drug some patients with lung or other cancers. In the induced or they may have a more organic cause. Eaton-Lambert syndrome, however, the muscles Drug induced dyskinesias are common in the get stronger rather than weaker with activity. elderly on long-term phenothiazine (anti-psy- A facial palsy may have a known cause or be chotic) medication which is usually reversible on idiopathic (Table 3). If the cause is not known the stopping the drug. Intracranial nerve compres- name Bell’s Palsy (Fig. 1) is applied. Other caus- sion may result in blepharospasm (contraction es must be excluded before this term is used. In of both eyelids). Hemifacial muscle spasm may Bell’s Palsy the onset is rapid, unilateral and occur and suggests a lesion eg of the cerebello- there may be an ache beneath the ear. The weak- pontine angle compressing the facial nerve. ness worsens over one to two days. If presenta- Whenever a facial tic is found, consideration tion is early, most clinicians give prednisolone should be given to referral for investigation for 5 days, the aim being to reduce neuronal since an underlying cause may often be treated. oedema. An eye patch is of value to protect the In the Ramsay-Hunt Syndrome, a profound cornea. The paralysis is of a lower motor neu- facial paralysis is accompanied by vesicles in the rone type in which all the facial muscles are pharynx on the same side and in the external affected on that side. In an upper motor neurone auditory meatus. It is thought that the geniculate lesion eg stroke, the forehead is spared since this ganglion of the facial nerve is infected with her- region is bilaterally represented in the cortex. pes zoster. BRITISH DENTAL JOURNAL VOLUME 195 NO. 1 JULY 12 2003 21
  4. 4. PRACTICE Table 4 Cranial nerve dysfunction and signs arising from it infective endocarditis which should be specifi- cally asked about. Signs and symptoms resulting Cranial nerve Possible problem Sign from a brain abscess depend on its location and I Olfactory Trauma, Tumour Decreased ability to smell CT and MRI scanning are useful in localisation II Optic Trauma, Tumour Blindness, visual field and diagnosis. Urgent surgical drainage is MS, Stroke defect required. III Oculomotor Diabetes, increased intra- Dilated pupil Cerebral Palsy is primarily a disorder of cranial pressure Ptosis motor function secondary to cerebral damage, IV Trochlear Trauma Diplopia most frequently associated with birth injury or V Trigeminal Sensory — idiopathic, None, sensory hypoxia. It is the most common cause of a con- trauma, IDN/Lingual deficit on testing nerve damage genital physical handicap, the patterns of which are variable. There are three main subtypes — Motor — Bulbar palsy Signs in IX, X, XI, XII spastic, ataxic and athetoid varieties. In the Acoustic Neuroma May be decreased facial sensation. spastic type the muscles are contracted and there Affects VIII also may be associated epilepsy. In the ataxic type, a VI Abducens MS, some strokes Inability of eye to look cerebellar lesion is responsible for a disturbance laterally Eye deviated towards nose of balance. Writhing movements characterise VII Facial LMN — Lower motor neurone Total the athetoid type of cerebral palsy. Bell's Palsy, Skull fracture Facial weakness In spina bifida, the vertebral arches fail to Parotid tumour fuse, possibly due to a deficiency of folic acid during foetal development. The condition may UMN — Upper motor neurone Forehead sparing lead to significant physical handicap such as an Stroke, Tumour weakness inability to walk, epilepsy or learning difficul- VIII Vestibulo- Excess noise; cochlear Paget's, acoustic neuroma Deafness ties. There may be an association with hydro- cephalus which often requires decompression IX Glosso- Trauma, Tumour Impaired gag reflex pharyngeal using a shunt. This is discussed further in the X Vagus Trauma, brainstem lesions Impaired gag reflex paediatric paper (Part 10 of this series). Soft palate moves to Patients with syringomyelia have a condi- ‘good’ side on saying tion in which cavitation of the central spinal 'aah'. cord occurs leading to a loss in pain and temper- XI Accessory Polio, stroke Weakness turning head ature sensibility. Syringobulbia is the term used away from affected side if the brain stem is affected — facial sensory loss (sternocleidomastoid). Weakness shrugging may occur, as may tongue weakness. shoulders (trapezius) An acoustic neuroma is a benign tumour XII Hypoglossal Trauma Tongue deviated to occurring at the cerebello-pontine angle on the Brainstem lesions affected side on vestibular part of the vestibulocochlear nerve. protrusion Cranial nerves V, VII, IX and X may also be involved leading to tinnitus, deafness and verti- go. Facial twitching, weakness or paraesthesias Infections affecting the nervous system may may occur. Other causes of facial sensory loss be bacterial or viral in origin. The possibility of (innervated by the trigeminal nerve except over bacterial meningitis should be borne in mind the angle of the mandible which is innervated by with maxillofacial injuries involving the middle cervical nerves) are given in Table 5. third of the face. Prompt treatment with antimi- Other neurological disorders that may be crobials (prophylactically in trauma cases) encountered include Huntington’s Chorea, should be undertaken. The viral type of menin- which is an autosomal dominant disorder where gitis is usually mild and self-limiting. The there is progressive dementia with marked invol- patient with meningitis has a severe headache, untary movements. The signs do not begin to feels sick or actively vomits and is often drowsy. The painful, stiff neck and aversion to light are Table 5 Potential causes of facial sensory loss well known. In meningitis caused by the bacteri- Intracranial um Neisseria meningitidis, a purpuric rash may be seen on the skin and can progress to adreno- • Neoplasm — Cerebral Tumour cortical failure as a result of bleeding into the • Inflammatory — MS adrenal cortex. Granulomatous conditions eg sarcoid TB Connective tissue disorders Herpetic encephalitis is rare, but should be treated promptly with aciclovir. In HIV associat- • Other : Paget’s Disease (nerve compression) Trigeminal Neuropathy ed neurological disease, a wide variety of infec- Cerebrovascular Disease tions and tumours are seen, for example lym- Extracranial phomas. Neurological effects of such lesions • Neoplasm — Cancer, Metastatic Cancers vary from fits to limb weakness. • Inflammatory — Osteomyelitis Brain abscess is a condition that may be sec- — Pressure from adjacent lesions ondary to oral sepsis4 or infection elsewhere eg • Trauma — Maxillary/mandibular fractures the middle ear or paranasal sinuses. A patient Iatrogenic eg removal of mandibular with congenital heart disease is also at increased third molars risk. Such abscesses can be a complication of 22 BRITISH DENTAL JOURNAL VOLUME 195 NO. 1 JULY 12 2003
  5. 5. PRACTICE appear until middle age. Friedreich’s Ataxia is an autosomal recessive or sometimes sex-linked cord degeneration of unknown cause. Severe ataxia and deformity occur and there may be associated cardiac disease with arrhythmias. GENERAL EXAMINATION The patient’s gait may give an immediate clue to an underlying neurological condition, for exam- ple the shuffling gait of Parkinsonism. A spastic gait is demonstrated by stiff limbs that are often swung around in a circular motion as the for- ward movement proceeds. The patient with a neurological condition Fig. 2 A patient with Sturge Weber Syndrome may appear confused. This may be for several reasons and a summary of potential causes is the cranial nerves in the following groups: ie given in Table 6. Raised intracranial pressure nerve(s) subserving the sense of smell, eyes, face, can occur following trauma to the head for mouth, neck and ears. A summary of disorders example in a patient attending with an injury affecting the cranial nerves and resulting signs associated with dental trauma. Such patients is given in Table 4. will complain of headache and may be restless Any changes in the sense of smell may reflect or vomiting. The classical sign of increased a problem with the olfactory nerve. Colds and blood pressure and decreased pulse rate occur sinusitis may be the cause but trauma involving and there is dilation of the pupil on the same side the cribriform plate can also cause the nerve to as the lesion. Patients with a head injury can be have impaired function. Some operations on the assessed according to the Glasgow Coma Scale nose may cause injury to the olfactory nerves. Visual acuity may be roughly assessed by Table 6 Possible causes of confusion that may be asking the patient to read a printed page. Defects encountered in a dental patient of the optic nerve may also affect the field of Hypoxia — Ensure clear airway, care with sedatives vision. A lesion of the cranial nerve III leads to complete or partial ptosis (drooping of the upper Epilepsy eyelid). The external ocular muscles are con- Infection — Significant oro-facial infection, pneumonia, meningitis trolled by the action of cranial nerves III, IV and VI. Disruption of the third nerve (which supplies Metabolic — Hypoglycaemia all of the extrinsic eye muscles apart from supe- Drug/Alcohol withdrawal rior oblique and lateral rectus) causes a paralysis Vascular — Stroke, MI of internal, upward and downward movement of Raised intracranial pressure the eye leading to double vision. The eye points Nutritional — Deficiency of various B vitamins downwards and outwards except when looking to the affected side. A fixed dilated pupil may also be seen. Disruption of IV, the trochlear (GCS) which involves three scored categories of nerve supplying superior oblique, prevents the Eye signs assessment — eye opening, muscle responses eye moving downwards and medially. The dou- and responses to vocal stimuli. ble vision is worse on looking down. Disruption Horner’s Syndrome comprises the four signs of VI (abducens supplying lateral rectus) causes Problems with cranial of a constricted pupil, ptosis (drooping of the an inability to abduct the eye (look to the ipsilat- nerves II, III, IV and VI upper eyelid), loss of sweating on the ipsilateral eral side). There is deviation of the eye towards affect the eyes face and enophthalmos. It is caused by interfer- the nose and double vision. ence with the cervical sympathetic chain eg after The muscles of facial expression are inner- a radical neck dissection, trauma to the neck or vated by the VII cranial nerve (facial nerve). As tumour. mentioned previously, upper motor neurone Patients with cerebral palsy have an lesions affecting the facial nerve eg after a increased incidence of dental malocclusion and stroke may be differentiated from lower motor abnormal movement of the oral and facial mus- neurone causes eg Bell’s Palsy since the latter culature that may cause difficulty in dental causes the whole side of the face to be weak- treatment provision. ened whereas the forehead is spared in an The Sturge-Weber syndrome (Fig. 2) describes upper motor neurone lesion due to bilateral an association between a facial port wine stain representation at the level of the cerebral cor- (haemangioma) with focal fits on the contralat- tex. The ipsilateral eye moves upwards on eral side. Exophthalmos and spasticity may also attempted closure of the eyes in Bell’s Palsy — be evident. The fits are caused by a capillary this is known as Bell’s Sign (Fig. 1). haemangioma in the brain. In terms of facial sensation the sensory divi- sion of the trigeminal (V cranial) nerve sub- CONSIDERATION OF THE CRANIAL NERVES serves this over most of the face. The oph- A systematic approach is needed for examining thalmic, maxillary and mandibular divisions the Cranial Nerves. One approach is to consider may be compared by testing skin sensation on BRITISH DENTAL JOURNAL VOLUME 195 NO. 1 JULY 12 2003 23
  6. 6. PRACTICE either side with a wisp of cotton wool. The treatment under LA, with or without sedation. corneal (blink) reflex is often the first clinical Ability to protect the airway is also relevant for deficit to be seen in trigeminal nerve lesions. the provision of GA since all these modes of The mouth can demonstrate signs of cranial treatment jeopardise the airway to some extent. nerve problems in the case of cranial nerves V Stroke patients may be taking anticoagulants, or (motor division), IX, X and XII. If the masseter may be hypertensive. muscles are palpated whilst asking the patient In both multiple sclerosis and motor neurone to clench the teeth and the motor division of V disease, the degree of compliance achievable for is inactive, the masseter on that side will not treatment is likely to be impaired. It is best to use Cranial nerves contract properly. With a unilateral lesion, the LA alone if possible. Limited mobility and/or mandible deviates to the weak side on opening associated psychological disorders may cause the mouth (V being motor to the pterygoid difficulties with treatment. Patients are better Defects in cranial muscles). treated sitting so that respiration is assisted as nerves V, IX, X and XII Asking the patient to say ‘aah’ will allow an much as possible since it may be impaired. appraisal of IX and X nerves. The ninth (glos- Patients with MS may be taking corticosteroids, have intra-oral sopharyngeal) nerve is mainly sensory for the particularly early in the disease. Care of the air- manifestations pharynx and palate and the tenth (vagus) mainly way may be made more difficult due to muscular motor. With a unilateral lesion of the vagus, the incoordination. soft palate is pulled away from the weaker side. Patients with Parkinson’s disease suffer from Lesions of both nerves lead to an impaired gag excess salivation, which can cause difficulties reflex. The twelfth (hypoglossal) nerve may be with visibility leading to problems not only pro- tested by asking the patient to protrude the viding the treatment itself but also for the safe tongue. The tongue deviates to the weaker side. provision of an anaesthetic. Anti-muscarinic To test the accessory (eleventh) cranial nerve drugs will reduce the salivation and degree of the patient should be asked to put their chin tremor. The autonomic insufficiency often found towards the left or right shoulder against resist- in these patients makes them liable to postural ance by the examiner. The sternocleidomastoid hypotension and poor candidates for general muscle (supplied by XI) does not function when anaesthesia. XI is affected. In myasthenia gravis, local anaesthesia is The eighth (vestibulocochlear) nerve has two the option of choice. Doses should be kept to a components — the vestibular (appreciation of minimum. Muscle fatigue appears to increase position and movements of the head) and the during the day and therefore treatment is best cochlear (responsible for hearing). Lesions of the carried out early. Intravenous sedation should nerve may cause hearing loss, vertigo or ringing not be given in a dental practice setting6 since in the ears (tinnitus). Special tests are needed to respiratory impairment may be worsened. test the balance and positional functions of the A small oral dose of a benzodiazepine is nerve. acceptable if the patient is very anxious about their treatment. For similar reasons general GENERAL AND LOCAL ANAESTHESIA, anaesthetics are also not advised if possible. In SEDATION AND MANAGEMENT addition, some of the agents used with GA eg CONSIDERATIONS IN THE DENTAL PATIENT the muscle relaxant suxamethonium or opioids WITH NEUROLOGICAL DISEASE eg fentanyl may have their effects potentiated Patients prone to syncope should be treated with in these patients. regard to avoidance of known precipitating fac- Patients with visual problems may be per- tors as far as possible. Treatment in the supine manently disabled or the disorder may be tran- position has obvious advantages. sient. It is important that a ‘tell-do’ approach is Epileptic patients referred for GA should used for these patients to minimise anxiety. It is not be given methohexitone or enflurane since worth bearing in mind in these patients that these are epileptogenic. It is important to other senses eg hearing may be heightened. ensure that an epileptic patient has taken their Diplopia can be a transient complication of LA normal medication on the day of the proce- as mentioned earlier. Other cranial nerve dure. Intravenous sedation is useful in manag- lesions of relevance include those affecting ing epileptic patients. The benzodiazepines cranial nerves IX and X since the gag reflex have anticonvulsant properties and anxiolysis may be impaired leading to potential airway should decrease the chances of a fit. When compromise, particularly if sedation or GA are treating epileptic patients with sedation sup- being used. plemental oxygen should be provided via a Patients with cerebral palsy may not be able nasal cannula.5 The use of the benzodiazepine to tolerate treatment under LA, and GA may be reversal agent flumazenil should be avoided in the only way of achieving it. In the athetoid patients with epilepsy as this drug can precipi- type, potential epilepsy should be borne in mind. tate convulsions. Anxiety will often worsen the effects of the cere- Patients who have had a CVA should have bral palsy and therefore premedication e.g. with treatment only when their condition has been diazepam is often wise. Patients with spina bifi- optimised if possible. There may be a loss of da have increased incidence of latex allergy. reflexes such as swallowing or the gag reflex, Such patients may be prone to postural hypoten- which has implications for the safe provision of sion and are therefore best treated sitting up. 24 BRITISH DENTAL JOURNAL VOLUME 195 NO. 1 JULY 12 2003
  7. 7. PRACTICE Epilepsy and renal anomalies may also be asso- immune complexes. The antigens can be as ciated. In Friedreich’s Ataxia, possible arrhyth- diverse as microorganisms or drugs. mias should be remembered. The anti-muscarinic anti-Parkinsonian drugs such as orphenadrine and benzhexol can pro- EFFECTS OF DRUGS USED IN NEUROLOGICAL duce dry mouth, which may increase caries inci- DISORDERS ON ORO-DENTAL STRUCTURES dence. In addition, the dopaminergic drugs such Drugs used to treat neurological conditions can as levodopa and co-careldopa may produce taste produce unwanted effects in and around the disturbances. mouth. Anticonvulsants have a number of unwanted effects of interest to dentists. Gingival SUMMARY overgrowth is a recognised side effect of pheny- As with disorders of other systems, neurological toin7 but may also occur with sodium valproate diseases impact on dental treatment provision, and ethosuximide. In addition, phenytoin causes both in terms of the treatment itself and the pro- taste disturbance and may produce Stevens- vision of safe methods of anaesthesia/analgesia Johnson syndrome. This drug may also affect to facilitate it. the teeth. It has been implicated in producing 1. Madland G, Newton-John T, Feinmann C. Chronic idiopathic hypercementosis and shortening of the roots.8 Orofacial pain: I: What is the evidence base? Br Dent J 2001; Sodium valproate may produce parotid gland 191: 22-24. enlargement. Lamotrigine may cause dry mouth 2. Nurmikko T J, Eldridge P R. Trigeminal neuralgia – pathophysiology, diagnosis and current treatment. Br J and Stevens-Johnson syndrome. Ethosuximide Anaesth 2001; 87: 117-132. may produce Stevens-Johnson syndrome and 3. Courtney D J, Thomas S, Whitfield P H. Isolated orbital gingival bleeding. Carbamazepine may produce blowout fractures: survey and review. Br J Oral Maxillofac xerostomia, glossitis and oral ulceration. Surg 2000; 38: 496-502. 4. Corson M A, Postlethwaite K R, Seymour R A. Are dental Stevens-Johnson syndrome is the name given to infections a cause of brain abscess? Case report and review a severe form of erythema multiforme. The latter of the literature. Oral Diseases 2001, 7: 61-65. predominantly affects young males and is char- 5. Meechan J G, Robb N D, Seymour R A. Pain and Anxiety Control for the Conscious Dental Patient. pp287-290. Oxford: acterized by mucosal lesions with or without Oxford University Press, 1998. skin lesions. The typical skin lesion is described 6. Malamed S F. Sedation: a Guide to Patient Management. 3rd as looking like a target as it consists of concen- ed. p595 – 596. St Louis: Mosby, 1995. tric erythematous rings. The rashes may appear 7. Hassell T M. Epilepsy and the Oral Manifestations of Phenytoin Therapy. Basle: Kruger, 1981. differently however, hence the name ‘multi- 8. Seymour R A, Meechan J G, Walton J G. Adverse Drug forme’. The aetiology of erythema multiforme is Reactions in Dentistry. 2nd ed. p 121. Oxford: Oxford not known but is thought to be a disorder of University Press, 1996. ONLINE SUBMISSION to the British Dental Journal From July 2002, the British Dental Journal at www.bdj.co.uk is pleased to be able to offer its authors the option to submit their manuscripts online. • Authors from anywhere in the world will be able to quickly and easily enter their contact details into an online form, and attach their manuscript files, either as separate text and graphics, or as an integrated file. • Author files will be automatically converted into a PDF (Portable Document Format) file, which can be approved by the author on screen prior to submission. Submissions will be promptly acknowledged by e-mail. Editors and referees will then view the PDF on the website — cutting out the time that manuscripts traditionally spend in the postal system. • Authors who, for whatever reason, are unable to submit online can also benefit from the timeliness of electronic peer review. Authors are encouraged to submit their manuscripts on disk, or if necessary hard copy submissions can be converted into PDF files using high- quality scanners. • Making use of online submission and electronic peer review will enable us to speed up the review process, providing a better and more efficient service to authors. For further information about submitting your paper electronically please e-mail: k.maynard@bda-dentistry.org.uk BRITISH DENTAL JOURNAL VOLUME 195 NO. 1 JULY 12 2003 25

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