FRCA Notes

Multiple Sclerosis

Resources

  • Multiple sclerosis (MS) is the most frequently occurring demyelinating neuromuscular disorder
  • It is a chronic, heterogenous, often-relapsing condition characterised by the development of CNS plaques
  • UK prevalence ≤0.2%
  • 3x female preponderance
  • Mean age at diagnosis 30yrs

  • Some genetic component;
    • Higher risk in monozygotic than dizygotic twins
    • Sibling risk 3-5%
    • Combined overall risk of 15% in first, second and third degree relatives

  • Although the precise cause is unknown, the most widely accepted theory is that of an inflammatory immune-mediated disorder
  • The major pathological mechanisms are:
    • Inflammation
    • Demyelination
    • Denervation

  • MS is characterised by periventricular inflammatory lesions (plaques)
  • These plaques cause axonal demyelination and destruction, with consequent weakness, spasticity and sensory dysfunction
  • Plaques can, however, be observed anywhere in the CNS, leading to variable clinical presentations

Cytokine imbalance

  • Up-regulation of pro-inflammatory cytokines e.g. IFN-ɣ, IL-2, TNFɑ
  • Down-regulation of anti-inflammatory cytokines e.g. IL-10, IL-4/5/13

Disease progression

  • Relapsing-remitting (85%)
  • Primary progressive
  • Secondary progressive
  • Progressive relapsing

  • There are multi-system effects of CNS demyelination
System Effect Anaesthetic consideration
Airway Bulbar dysfunction Aspiration risk
Respiratory Central hypoventilation
Neuromuscular weakness		 Risk of ventilatory insufficiency or respiratory failure
Cardiovascular Autonomic dysfunction Haemodynamic lability
Neurological Sensory deficits
Motor deficits
Visual disturbances
Neuropathic pain		 NMBA resistance or sensivity both described
Chronic pain
Genitourinary Bladder dysfunction
Psychiatric/cognitive Cognitive decline
Mood changes		 Consent issues

Pregnancy

  • Pregnancy generally reduces the frequency of relapses, especially in the third trimester
  • Due to hormone-induced reduction in cell-mediated immunity

  • There are no increased rates of maternal or infant perinatal complications in patients with MS
  • There is a slightly increased risk of longer post-partum stay in MS patients, though this is not an association of higher LSCS rates

  • There may be post-delivery or post-operative disease relapse
    • Highest risk in first 3 months post-partum
    • Due to changing hormonal landscape

  • Post-partum relapses are not associated with particular anaesthetic techniques nor the need for LSCS
  • The highest risk is in those with higher disability score at conception or higher frequency of relapses in the year pre-conception

Diagnosis

  • Ultimately a clinical diagnosis
  • T2-weighted brain MRI typically used to confirm diagnosis/exclude differentials e.g. vasculitides, sarcoidosis, spinocerebellar degeneration, leukodystrophy

Management

  • Long-term management is with immunosuppression:
    • Cyclophosphamide
    • Azathioprine
    • Methotrexate
    • Cyclosporin A

  • Acute relapses are treated with:
    • Steroids e.g. dexamethasone, methylprednisolone (NB dexamethasone crosses the placenta and should be avoided in the first trimester)
    • IVIg

  • Neuropathic pain is managed in a conventional fashion

Perioperative management of the patient with multiple sclerosis


  • Standard pre-operative assessment
  • Suitable antacid premedication in view of raised aspiration risk
  • Consider glycopyrrolate for significant secretions

Avoid exacerbating disease

  • Demyelinated axons demonstrate increased sensitivity to:
    • Local anaesthetics
    • Heat; temperature monitoring and management should be employed to avoid hyperthermia

  • There is some controversy about the suitability of local anaesthetics in patients with MS
    • Some sources suggest avoiding neuraxial techniques, or using epidural preferentially to spinal anaesthetic to reduce the CSF LA burned
    • Others suggest neuraxial and RA techniques are acceptable
    • Peripheral nerve blocks are safe as the disease is confined to the neuraxis

General anaesthetic

  • Consider I&V with RSI technique due to high aspiration risk

  • Non-depolarising NMBA can typically be used safely and in normal doses, though there are reports of both resistance (extra-junctional nAChR) and sensitivity (reduced muscle mass)
  • Depolarising agents should be used with caution, especially if the patient is immobile, owing to the hyperkalaemia risk
  • In general avoid NMBA where possible and, if used, reverse fully

Obstetrics

  • Neuraxial techniques are not contraindicated
    • No correlation between neuraxial techniques and MS relapse post-partum
    • Use the lowest effective dose of LA to minimise CSF exposure and toxicity

  • Most immunomodulatory and disease modifying treatments are discontinued prior to conception
  • Relapses in the antenatal period are treated with high-dose steroids, IVIg or plasma exchange

  • Multi-modal analgesia to avoid:
    • Opioid-induced exacerbations of respiratory function
    • Stress-induced exacerbations of neuromuscular disease

  • Chest physiotherapy to aid secretion clearance and respiratory optimisation
  • Ongoing temperature management