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



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



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



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



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



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



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



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




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




Natural Progression of Parkinsonism

0

20

40

60

80

100

5 years 10 years 15 years 20 years

Funct

ional Capaci

ty

ON MedsOFF Meds



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




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



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!”



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



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



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



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



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



Multiple Sclerosis

No specific contra-indication to general or local anaesthesia

Surgical trauma is not likely to cause exacerbation of the condition



Spinal Cord Injury – AetiologyAetiology Number Percent

AutomobileFallGunshotDivingOther traumaMotorcycleSportsMedicalPedestrianOther UnknownTotal

1112919310278254149142131946049

3498

3226987444321

100



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



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



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®)



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



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



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



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



Stroke – Unmodifiable Risks

Age – majority occur in individuals >65 Male gender Race – higher incidence in African Americans Heredity



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



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



Stroke Prevention

Risk factor modification Aspirin

Dose between 81 and 325 mg/day Ticlopidine (Ticlid®) Clopidogrel (Plavix®) ASA/persantine (Aggrenox®)

Warfarin



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



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



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?



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



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



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



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




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




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




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




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



Finis

20. neurology

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