Neurology Neurology

Multiple Sclerosis Features

Multiple sclerosis (MS) is the most common disabling neurological disease in young adults. It is characterised by demyelinating lesions disseminated in time and space.

✦ The Mnemonic

"DISSeminated in Time and Space — MISS: Motor, Internuclear, Sensory, Sphincter"

Motor · Internuclear ophthalmoplegia · Sensory · Sphincter/autonomic

M Motor UMN signs — spasticity, weakness, hyperreflexia, Babinski positive; asymmetric onset

I Internuclear ophthalmoplegia Bilateral INO = MS until proven otherwise; MLF plaque; adduction failure + nystagmus

S Sensory Paraesthesia, numbness; Lhermitte's phenomenon — electric shock sensation on neck flexion

S Sphincter/autonomic Bladder dysfunction (urgency, retention); erectile dysfunction; fatigue (most common overall symptom)

V Visual Optic neuritis — painful vision loss in one eye; relative afferent pupillary defect; most common first presentation

📚 Clinical Breakdown

McDonald criteria (2017): diagnosis requires dissemination in space (lesions in ≥2 CNS areas) and dissemination in time (lesions at different time points) — or CSF oligoclonal bands in place of DIT. MRI is central to diagnosis — periventricular, juxtacortical, infratentorial, and spinal cord lesions are the four characteristic locations.

Disease-modifying therapies (DMTs): interferon-beta and glatiramer acetate (injectable, low-moderate efficacy); natalizumab, fingolimod, dimethyl fumarate (high efficacy oral/IV); alemtuzumab, ocrelizumab, cladribine (very high efficacy, significant risk). Early aggressive therapy improves long-term outcomes.

Optic neuritis: unilateral painful vision loss over days, colour desaturation (red-green), relative afferent pupillary defect (RAPD — swinging light test). MRI of optic nerves shows enhancement. Most patients recover vision over weeks. 50% develop MS within 15 years if MRI brain is abnormal at presentation.

Most common first symptom Optic neuritis

Bilateral INO Pathognomonic of MS in young patients

Lhermitte's phenomenon Electric shock on neck flexion — cervical cord lesion

Oligoclonal bands CSF IgG bands — 95% sensitivity for MS

⭐ Clinical Pearl

Uhthoff's phenomenon: temporary worsening of neurological symptoms with heat (hot bath, exercise, fever). Caused by impaired conduction in demyelinated axons at elevated temperatures. This is NOT a relapse — symptoms resolve with cooling. Important to distinguish from true relapse when counselling patients.