20. Neurology
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Transcript of 20. Neurology
The University of Western Ontario
Paul E. Cooper, MD, FRCPC 1
NEUROLOGY AND THEDENTAL PATIENT
Paul E. Cooper, MD, FRCPC,
Associate ProfessorDepartment of Clinical Neurological SciencesDivision of Neurology
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Outline Epilepsy
Management of the patient with epilepsy Management of peri-operative seizures
Parkinson’s Disease Alzheimer’s 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-limited—i.e. they
stop on their own, without medication intervention
If more than 1 seizure—consider the possibility of underlying abnormality—e.g. electrolyte disturbance, hypoglycaemia
For seizures that are prolonged—i.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 patient’s pre-operative anticonvulsant levels Consult with patient’s neurologist or family physician
Most stable epileptics, well-controlled on medication, can undergo surgery without difficulty or complication
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Parkinson’s 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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Parkinson’s 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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Parkinson’s Disease
Natural Progression of Parkinsonism
0
20
40
60
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5 years 10 years 15 years 20 years
Funct
ional Capaci
ty
ON MedsOFF Meds
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Parkinson’s 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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Parkinson’s Disease
Patients with Parkinson’s disease, especially older patients are at higher risk of post-operative confusion and delirium
Avoid treatment with major tranquillizers as this will worsen the parkinson’s disease
Atypical antipsychotic medication is preferable
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Alzheimer’s 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
Cooper’s Rule of Memory Disturbance: “AS LONG AS YOU ARE WORRIED ABOUT YOUR
MEMORY—YOU HAVE NOTHING TO WORRY ABOUT!”
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Alzheimer’s 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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Alzheimer’s 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 lighting—can lead to hallucinations Use night-time sedation with caution—major
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 >25 years Diagnosis is clinical with confirmatory evidence
provided by MRI scanning and CSF examination
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Multiple Sclerosis
Curious geographic distribution—uncommon 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 courses—usually 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 – AetiologyAetiology Number Percent
AutomobileFallGunshotDivingOther traumaMotorcycleSportsMedicalPedestrianOther UnknownTotal
1112919310278254149142131946049
3498
3226987444321
100
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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 output—e.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 >65 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 136:108-10
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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 82:360-5
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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 52:214-6
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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