FRCA Notes

Parkinson's Disease

Parkinson's disease isn't explicitly mentioned in the curriculum, falling under the generic banner of 'preoperative assessment & optimization of', and 'principles of anaesthesia' for, patients with neurological disease.

Nevertheless it was a CRQ in 2020 (71% pass rate), with lost marks on the pharmacology of Parkinson's drugs.

A repeat CRQ in 2023 (59% pass rate) saw candidates fall down on the pharmacology again, namely drugs which can be given non-enterally and withdrawal side-effects.

Resources

  • Idiopathic Parkinson's disease is a common neurodegenerative disorder
  • It poses perioperative challenges owing to the multi-system effects of the disease and the need to ensure adequate anti-Parkinsonian medication delivery
  • Loss of dopaminergic neuronal pathways in the pars compacta of the substantia nigra
  • There is considerable dopaminergic neuronal reserve, so symptoms only manifest when 70% of dopaminergic neurones are lost
  • The precise mechanism for the degeneration is unknown, although age is the single most consistent risk factor

Dopamine production

  • Dopamine is a naturally occurring catecholamine hormone and neurotransmitter
  • It is produced in a series of steps:
    1. The amino acid phenylalanine is metabolised by phenylalanine hydroxylase to tyrosine, mainly in the liver
    2. Tyrosine is actively concentrated in the cytoplasm of adrenergic neurones
    3. Tyrosine is metabolised to DOPA by the enzyme tyrosine hydroxylase, which is the rate-limiting step in the process
    4. DOPA is metabolised to dopamine by DOPA-decarboxylase

  • The classic Parkinsonian motor symptoms are a triad of:
    1. Bradykinesia
    2. Muscle rigidity
    3. Asymmetric resting tremor

Other symptoms in Parkinson's disease

Constitutional Motor Neuropsychiatric Autonomic symptoms
Fatigue Altered gait Depression/anxiety Postural hypotension
Sleep disturbance Micrographia Cognitive disturbance Sialorrhoea
Constipation Dysphagia Dementia Urinary dysfunction
Soft speech Sexual dysfunction
Expressionless (mask-like) face Excessive sweating
Postural instability

Differential diagnosis of Parkinsonian features

  • Idiopathic Parkinson's disease (85% of those with Parkinsonism)
  • Parkinson's plus syndromes
    • Multi-system atrophy
    • Progressive supranuclear palsy
  • Vascular e.g. multi-infarct disease, arteriosclerosis
  • Wilson's disease
  • Iatrogenic e.g. reserpine, anti-dopaminergic drugs such as prochlorperazine
  • Infectious e.g. post-encephalitis
  • Trauma e.g. dementia pugilistica
  • Metabolic e.g. hypoparathyroidism
  • Neoplastic e.g. space-occupying lesion

  • Pharmacological management aims to manage symptoms via supplementation of CNS dopamine
Class Examples Common side-effects
Dopamine precursor +
DOPA decarboxylase inhibitor		 Levodopa - carbidopa
Levodopa - benserazide		 N&V
Orthostatic hypotension
Dyskinesia
Hallucinations
Dopamine agonist Pramipexole
Ropinirole
Apomorphine (subcutaneous)
Rotigotine (transdermal)		 Nausea
Highly emetogenic (apomorphine)
Impulsive control disorders
Orthostatic hypotension
Somnolence
MAO-I Selegiline
Rasagiline		 Headache
Arthralgia
COMT-I Entacapone
Tolcapone		 Dark urine

Non-enteral drugs

  • For PD patients in whom the oral route is not possible, two drugs are available:
  1. Apomorphine
    • Given by subcutaneous infusion
    • Highly emetogenic
    • Can cause profound hypotension

  2. Rotigotine
    • Given by transdermal patch
    • Not sufficiently potent to manage patients on higher dose anti-PD drug regimes

Withdrawal symptoms

  • Levodopa → Parkinson-hyperpyrexia syndrome
    • Similar to NMS; fever, muscle rigidity, CVS instability and altered mental status

  • Dopamine agonists → dopamine agonist withdrawal symptoms (DAWS)
    • Anxiety | nausea | depression | pain | orthostatic hypotension

Airway

  • Upper airway dysfunction from laryngeal dyskinesia
    • Secretions and aspiration can occur
    • There is higher chance of post-extubation laryngospasm

  • Fixed flexion deformity of the neck may impair laryngoscopic view

Respiratory

  • Respiratory muscle rigidity, bradykinesia or dyskinesia can cause a restrictive pulmonary deficit
  • In time leads to pulmonary hypertension

Cardiovascular

  • Orthostatic or exercise-induced hypotension may be due to the PD or pharmacological management
  • Patients are prone to intra-operative hypotension
  • Increased incidence of arrhythmias

Neurological

  • Higher incidence of post-operative delirium (60%) and hallucinations

Renal

  • Increased risk of post-operative UTI

Gastrointestinal

  • Dysphagia contributes to aspiration and malnutrition
  • Sialorrhoea from impaired swallowing may require anticholinergic premedication
  • Increased prevalence of GORD
  • Post-operative ileus may impact on absorption of anti-Parkinsonian drugs
  • Dopaminergic anti-emetics are contra-indicated

Perioperative management of the patient with Parkinson's Disease


  • Comprehensive pre-assessment, especially as many PD patients will be elderly with comorbid disease
  • Optimisation by PD physicians
  • Plan for perioperative management of PD drugs
    • Usually allow patients to take drugs within the NBM period
    • Utilise anaesthetic techniques to minimise time to return of enteral route
    • Levodopa can be given NG/NJ
  • First on the operating list to ensure predictable timing of surgery and therefore drug administration
  • Emergency surgery may require use of apomorphine infusion

Monitoring and access

  • AAGBI, acknowledging that:
    • NIBP may be affected by tremor and motion artefact
    • ECG may be affected by tremor causing motion artefact, which may look like AF
    • ECG may be affected by sweating from autonomic dysfunction, which may impair electrode placement
  • Lower threshold for an arterial line given risks of autonomic dysfunction

Anaesthetic technique

  • Regional anaesthesia offers several benefits:

    • Benefits of RA in Parkinson's disease
    Able to monitor Parkinsonian symptoms intra-operatively
    Can give oral medication intra-operatively
    Early return to post-operative oral intake
    Reduced use of systemic opioids (may decrease GI function)
    No use of NMBA

  • However, administering neuraxial or regional anaesthesia may be difficult due to rigidity or tremor
  • Furthermore, areas not affected by block may still be tremulous, which can impair surgery

  • Although GA eliminates tremor, issues such as PONV and increased incidence of pneumonia make it less appealing
  • If GA is used, consider pre-medication with anti-sialagogue and an RSI technique due to risk of aspiration

Drugs

  • Although propofol can cause dyskinesia as in the general population, its anti-emetic and tremor-suppressing effects make it a suitable induction agent
  • Thiopentone and ketamine are both safe too

  • Volatile agents are all safe except halothane, which potentiates levodopa-induced arrhythmias

  • NMBA are safe although avoid neostigmine

  • Opioids are safe except pethidine, which may precipitate serotonin syndrome

  • Consider HDU admission
  • Return to enteral anti-PD drugs ASAP, although can use transdermal rotigotine/IV apomorphine/NG or NJ levodopa
  • Multimodal analgesia; PCA may be difficult to use due to rigidity/tremor

  • Post-operative delirium (60%) and hallucinations are more common
    • Dopaminergic drugs are contraindicated
    • Lorazepam or quetiapine are options

Anti-emetics

Safe Do not use
Ondansetron Metoclopramide
Domperidone (doesn't cross BBB) Butyrophenones (haloperidol, droperidol)
Cyclizine Phenothiazines (prochlorperazine, chlorpromazine)
Dexamethasone