Multiple Sclerosis (MS) is a classic "bread and butter" topic for the UKMLA AKT. It’s the most common cause of non-traumatic neurological disability in young adults, and the examiners love testing your ability to distinguish the types and understand the diagnostic criteria.

Let's break this down into the four key areas you asked about.

1. Types of Multiple Sclerosis

The clinical course of MS is variable, but it generally falls into these categories:

• Relapsing-Remitting MS (RRMS): The most common initial presentation (approx. 85%). Patients have clearly defined "attacks" (relapses) followed by periods of complete or partial recovery (remissions).
• Secondary Progressive MS (SPMS): Many patients with RRMS eventually transition into this phase, where there is a steady worsening of neurological function over time, with or without occasional relapses.
• Primary Progressive MS (PPMS): Steady worsening of symptoms from the very beginning, without distinct relapses or remissions.
• Progressive-Relapsing MS: A rarer form characterized by a steady decline from onset but with clear acute relapses along the way.

2. McDonald Criteria (2017 Revision)

The gold standard for diagnosis is demonstrating dissemination in space (DIS) and dissemination in time (DIT).

• Dissemination in Space: Lesions in at least 2 of the 4 classic MS areas (periventricular, juxtacortical/cortical, infratentorial, or spinal cord).
• Dissemination in Time:
  • A new lesion on a follow-up MRI compared to a baseline scan.
  • Presence of both enhancing (active) and non-enhancing (old) lesions on a single scan.
  • Crucial UKMLA point: The presence of CSF-specific oligoclonal bands can now be used to substitute for DIT in patients with a typical clinically isolated syndrome.

3. MRI Findings

MRI is the imaging modality of choice (specifically T2-weighted and FLAIR sequences).

• Dawson’s Fingers: Periventricular demyelinating lesions oriented perpendicular to the lateral ventricles (representing inflammation around the medullary veins).
• Hyperintense lesions: Seen on T2/FLAIR.
• Gadolinium enhancement: Indicates an "active" lesion where the blood-brain barrier is currently disrupted.
• "Black holes": T1-weighted hypointensities that represent permanent axonal loss.

4. Disease-Modifying Therapies (DMTs)

Management is split into treating acute relapses (usually high-dose steroids like Methylprednisolone) and long-term prevention with DMTs.

I've put together a table of the common DMTs you'll encounter in UK practice to help you keep them straight.