NEUROLOGY AND THE DENTAL PATIENT

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NEUROLOGY AND THEDENTAL PATIENT

• Paul E. Cooper, MD, FRCPC,
• Associate Professor
• Department of Clinical Neurological Sciences
• Division of Neurology

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Outline

• Epilepsy
• Management of the patient with epilepsy
• Management of peri-operative seizures
• Parkinsons Disease
• Alzheimers disease
• Multiple Sclerosis
• Paraplegia
• Stroke
• Management of the TIA/Stroke Patient
• Prevention of peri-operative stroke
• Silver Amalgam Fillings

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Epilepsy

• Definition a state of recurrent seizures, not
  due to an identifiable metabolic cause
• May be due to underlying genetic or congenital
  factors or to cerebral insult prenatally or later
  in life
• Type of Epilepsy is important
• Convulsive Seizures
• Non-convulsive seizures are seldom dangerous to
  the patient

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Epilepsy

• What might cause an otherwise stable patient to
  have a seizure?
• forgetting to take anticonvulsant
• Stress emotional/physical
• Sleep disturbance
• Hypoglycaemia
• Alcohol withdrawal
• Other medications
• See next slide

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Medications Associated with Seizures

• Anaesthetics local and general
• Anticonvulsants withdrawal from esp.
  benzodiazepines
• Antidepressants
• Antipsychotics
• Antihistamines
• Antibiotics
• CNS stimulants
• Theophylline, caffeine, cocaine, amphetamine
• Nonsteroidal anti-inflammatory agents
• Opiates

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Epilepsy

• Most epileptic seizures are self-limitedi.e.
  they stop on their own, without medication
  intervention
• If more than 1 seizureconsider the possibility
  of underlying abnormalitye.g. electrolyte
  disturbance, hypoglycaemia
• For seizures that are prolongedi.e. longer than
  10 minutes or that re-occur without the patient
  regaining normal consciousness Rx with
• Lorazepam (Ativan) 0.05 1 mg/kg IV to
  maximum of 4 mg may repeat x1
• Be prepared to bag patient

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Epilepsy

• Prevention of Peri-operative Seizures
• Patients must take their anticonvulsant
  medication
• If general anaesthetic anaesthetist should be
  aware of seizure tendency
• Check patients pre-operative anticonvulsant
  levels
• Consult with patients neurologist or family
  physician
• Most stable epileptics, well-controlled on
  medication, can undergo surgery without
  difficulty or complication

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Parkinsons Disease

• Definition a movement disorder of unknown cause
  that primarily affects the pigmented,
  dopamine-containing neurons of the substantia
  nigra causing
• Bradykinesia slowness of movement
• Rigidity
• Tremor
• In later stages, about 20 of patients will also
  have dementia

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Parkinsons Disease

• Treatment has no effect on the progression of the
  disease
• While clinically the patient may seem little
  affected, if the medication is stopped, major
  symptoms will be revealed

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Parkinsons Disease
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Parkinsons Disease

• Patients must continue with their medications
• If unable to swallow, post-surgery,
  hospitalization will be necessary
• Off meds much higher risk of aspiration and
  pneumonia
• Sudden withdrawal of dopaminergic medication may
  lead to neuroleptic malignant syndrome
• Fever
• Movement disorder rigidity
• Altered mentation

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Parkinsons Disease

• Patients with Parkinsons disease, especially
  older patients are at higher risk of
  post-operative confusion and delirium
• Avoid treatment with major tranquillizers as this
  will worsen the parkinsons disease
• Atypical antipsychotic medication is preferable

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Alzheimers Disease

• The most common cause of dementia
• The memory dysfunction involves impairment of
  learning new information
• Contrast with benign forgetfulness
• Baby Boomers often complain of K-R-A-F-T
• Coopers Rule of Memory Disturbance
• AS LONG AS YOU ARE WORRIED ABOUT YOUR MEMORYYOU
  HAVE NOTHING TO WORRY ABOUT!

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Alzheimers Disease

• Treatment
• Donepizil (Aricept) inhibits cholinesterase
• May increase risk of local anaesthetic toxicity
• Lowers seizure threshold
• Rivastigmine (Exelon) inhibits cholinesterase
• Similar to donepizil
• Galantamine (Reminyl) inhibits cholinesterase
• Similar to donepizil and rivastigmine

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Alzheimers Disease

• Greater risk of post-operative confusion/delirium
• Hospitalized patients very likely to become more
  confused
• Make hospital staff aware of Alzheimer diagnosis
• Continuous presence of a family member often has
  a calming effect
• Avoid low level lightingcan lead to
  hallucinations
• Use night-time sedation with cautionmajor
  tranquillizer may be a better choice

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Multiple Sclerosis

• Definition a slowly progressive CNS disease
  characterized by disseminated patches of
  demyelination in the brain and spinal cord,
  resulting in multiple and varied neurologic
  symptoms and signs, usually with remissions and
  exacerbations
• Course is highly varied and unpredictable and in
  most patients remittant
• Some patients present with tic douloureux
• Average illness lasts gt25 years
• Diagnosis is clinical with confirmatory evidence
  provided by MRI scanning and CSF examination

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Multiple Sclerosis

• Curious geographic distributionuncommon in the
  tropics
• Migration data suggest important childhood
  exposure to an, as yet, unknown agent is
  important
• May be related to early exposure to vitamin D

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Multiple Sclerosis

• Few if any surgical considerations per se
• Many patients will have received prednisone in
  short coursesusually not sufficient to cause
  adrenal insufficiency
• Treatment with interferons
• May be associated with seizures
• No significant drug interactions

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Multiple Sclerosis

• No specific contra-indication to general or local
  anaesthesia
• Surgical trauma is not likely to cause
  exacerbation of the condition

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Spinal Cord Injury Aetiology
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Spinal Cord Injury

• ONE CAN EXPECT 906 INJURIES PER YEAR PER MILLION
  POPULATION
• The effect of the injury depends on the level
• Above C5 respiratory paralysis often death
• At or above C4 to C5 complete quadriplegia
• Between C5 and C6 paralysis of legs but arm
  abduction and flexion possible
• Between C6 and C7 paralysis of legs, wrists and
  hands but shoulder movement and elbow flexion
  usually possible

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Spinal Cord Injury

• Between T11 and T12 Paralysis of leg muscles
  above and below knee
• At T12 to L1 Paralysis below the knee
• Cauda Equina hyporeflexic or areflexic paresis
  of lower extremities and usually pain and
  hyperaesthesia in the distribution of the nerve
  roots
• 3rd, 4th and 5th sacral nerve roots or conus
  medullaris at L1 complete loss of bladder and
  bowel control and sexual function

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Spinal Cord Injury

• The entire sympathetic nervous system is isolated
  from the brain in patients with complete cervical
  spine lesions
• This can lead to autonomic dysreflexia in which
  stimuli such as bladder distention or pressure
  sores can result in increased sympathetic
  outpute.g. sweating and hypertension
• Hypotension can also be seen
• Spasticity is treated with a variety of
  medications that may be of significance in the
  surgical setting e.g. diazepam (Valium),
  baclofen (Lioresal) and tizanidine (Zanaflex)

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Drugs Used in Spinal Cord Disease

• Tizanidine (Zanaflex) may cause hypotension or
  potentiate the hypotensive effect of other
  medications
• Baclofen (Lioresal) and diazepam (Valium), if
  withdrawn abruptly can cause seizures,
  hallucinations, confusion and manic-like episodes
• High doses of corticosteroids may be used in the
  initial post-injury management of these patients
  but will not have a significant effect on adrenal
  function and probably have no effect on healing
  ability

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STROKE and TIA

• Cerebrovascular disease is the most common cause
  of neurologic disability in Western countries
• Major types of cerebrovascular disease
• Cerebral insufficiency
• Infarction
• Haemorrhage
• Arteriovenous malformation
• Stroke ischaemic lesions

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TIA

• TIA transient ischaemic attack
• Focal neurologic abnormalities of sudden onset
  and brief duration (usually minutes, never more
  than a few hours) that reflect dysfunction in the
  distribution of either the internal
  carotid-middle cerebral or the vertebral-basilar
  arterial system

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Stroke

• 80 involve the carotid system
• 3rd leading cause of death in US and Canada
• Major cause of disability
• Most stroke survivors die of myocardial disease

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Stroke Unmodifiable Risks

• Age majority occur in individuals gt65
• Male gender
• Race higher incidence in African Americans
• Heredity

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Stroke Modifiable Risks

• Hypertension
• Diabetes mellitus
• Cigarette smoking
• Alcohol
• Obesity
• Hyperlipidaemia
• Cardiac disease esp. previous myocardial
  infarction and atrial fibrillation
• Haematologic factors e.g. hyperhomocystinaemia

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Treatment of Acute Stroke

• In a non-post-operative patient, tPA (tissue
  plasminogen activator) can be given intravenously
  within 3 hours of onset of stroke symptoms and
  intra-arterially within 6 hours
• The best treatment is prevention

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Stroke Prevention

• Risk factor modification
• Aspirin
• Dose between 81 and 325 mg/day
• Ticlopidine (Ticlid)
• Clopidogrel (Plavix)
• ASA/persantine (Aggrenox)
• Warfarin

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Stroke and Surgery

• For elective surgery delay for 2-3 months
  post-event
• Do not stop ASA or antiplatelet agent
• Remember high incidence of ischaemic coronary
  artery disease in patients with TIA or stroke

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Stroke and Surgery

• 30 million patients in USA undergo non-cardiac
  surgery annually
• 1.5 million suffer post-operative cardiovascular
  events
• Surgical trauma associated catecholamine release
  leads to platelet activation
• Platelet activation promotes platelet aggregation
  and hypercoagulability
• Aspirin is not routinely started in the immediate
  peri-operative period
• Even in high risk patients already taking
  aspirin, it is generally discontinued a week
  prior to elective surgery to improve
  intra-operative hemostasis

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Stroke and Surgery

• The risk-to-benefit ratios of administering vs
  withholding aspirin in the immediate
  peri-operative period have never been assessed
  and compared
• There are no large randomized controlled trials
  available to guide us
• WHAT DOES THE LITERATURE SAY?

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Aspirin and Surgery

• Gaspar et al. Department of Oral and
  Maxillofacial Surgery, Rambam Medical Center,
  Haifa
• CONCLUSION discontinuing low-dose aspirin prior
  to elective oral surgery is not justified
• Harefuah 1999 136108-10

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Aspirin and Surgery

• Sonksen et al. Dept. of Anaesthesia, City
  Hospital, Birmingham, UK
• Conclusion in healthy volunteers the defect in
  haemostasis has largely disappeared 48 hours
  after the last dose
• British Journal of Anaesthesia 1999 82360-5

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Aspirin and Surgery

• Bartlett Department of Plastic, Reconstructive,
  Hand and Maxillofacial Surgery, Middlemore
  Hospital, Auckland, New Zeland
• Conclusion it is unnecessary to stop aspirin
  before minor dermatologic plastic surgery
• British Journal of Plastic Surgery 1999 52214-6

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Aspirin and Surgery

• Ardekian et al. Department of Oral and
  Maxillofacial Surgery, Rambam Medical Center,
  Haifa, Israel
• Conclusion low-dose aspirin should not be
  stopped before oral surgery
• Journal of the American Dental Association 2000
  131 1398, 1401-2

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Silver Amalgam Fillings

• the general population is exposured to mercury
  primarily via food and dental amalgam
• fish is a major source of methyl mercury
• corrosion of fillings results in liberation of
  mercury
• the rate has been estimated as 1-5 µg/24 hours

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Silver Amalgam Fillings

• no harmful effects have every been demonstrated
  in well-controlled clinical trials
• toxicity is dose dependent
• blood and urine mercury levels in patients with
  amalgam fillings are well below (less than one
  tenth) acceptable safety levels
• combined mercury intake from food and amalgam
  does not exceed the acceptable daily intake

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Silver Amalgam Fillings

• micromercurialism or metal syndrome
• claimed to be related to amalgam fillings
• various CNS, muscle, joint and GI symptoms
• the symptoms are non-specific
• relationship to mercury exposure is weak
• similar symptoms can be seen with other exposures
• psycho-social conditions may play an important
  role

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Silver Amalgam Fillings

• at present, there is no convincing evidence that
  removal of fillings is of any benefit to health
• if anything, removal would temporarily increase
  exposure to mercury

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Finis