Mastering Upper and Lower Limb Neurology for MRCP PACES

Ask any cohort of PACES candidates which cases they fear most, and limb neurology tops the list. It is fast-moving, unforgiving of a clumsy technique, and exposes within seconds whether you have genuinely examined neurological patients or only read about them. Yet it is also one of the most predictable parts of the exam. The same handful of conditions rotate through the carousels year after year, and the examiners are looking for a recognisable, senior-level routine rather than perfection. Cranial nerves and the cerebellar system deserve their own preparation, but this guide completes the trilogy: the upper and lower limb neurological examination for MRCP PACES.

Why Limb Neurology Deserves Your Best Revision Time

• Neurological cases appear in the overwhelming majority of PACES carousels, usually as a patient with physical signs rather than a simulated scenario.

• A single limb case simultaneously tests your physical examination, differential diagnosis, clinical judgement and communication with the patient — four marking domains at once.

• The cases are strikingly reproducible. Stroke, peripheral neuropathy, motor neurone disease, Charcot-Marie-Tooth disease, hereditary spastic paraparesis and old polio account for most encounters.

• Candidates who present a clean pattern and a unifying diagnosis routinely outperform candidates with technically flawless but aimless examinations.

What PACES23 Asks of You

In the refreshed PACES23 format, all five 20-minute stations are broad clinical encounters. You get a short period to read the scenario, then roughly fourteen minutes of patient-facing time in which you may need to take a focused history, examine, and speak with the patient before structured questioning. The implication for neurology is crucial: you no longer have the luxury of an exhaustive screen. You need a targeted, hypothesis-driven examination that finishes on time and leaves space to communicate and answer. Practise your limb routine to a strict clock until it fits comfortably inside ten minutes.

The Golden Rule: Examine to a Pattern, Not a Protocol

Every limb finding should feed one central question: which system is affected?

1. Upper motor neurone — increased tone, pyramidal weakness, brisk reflexes, clonus, upgoing plantar

2. Lower motor neurone — wasting, fasciculations, flaccid tone, absent reflexes

3. Cerebellar — hypotonia, pendular reflexes, incoordination out of proportion to weakness

4. Extrapyramidal — rigidity, bradykinesia, tremor, postural change

Overlay a sensory map (peripheral, hemisensory, level, dissociated) and you can localise almost any PACES case before the examiner opens their mouth.

The Upper Limb: A Station-Safe Sequence

1. Inspection (sixty seconds that earn marks)

Before touching the patient, rest their hands comfortably on a pillow or their lap, expose to above the elbow, and wait. Fasciculations need warm, rested muscles and patience — the classic mark dropped is the twitching tongue or thenar eminence missed because you rushed. Look for wasting (thenar, hypothenar, first dorsal interosseous, forearm, shoulder girdle), posture, tremor, scars, contractures and skin changes.

2. Tone

Ask the patient to let their arm go loose. Roll the wrist, then flex and extend the elbow, then passively pronate and supinate the forearm. Feel for spasticity (velocity-dependent, clasp-knife release), lead-pipe rigidity, cogwheeling, or the flaccidity of a lower motor neurone lesion.

3. Power

Screen first with pronator drift: arms outstretched, eyes closed. A downward drift with pronation suggests subtle pyramidal weakness; a rising limb suggests loss of position sense.

Then test movements distal to proximal using the MRC scale: finger abduction, thumb abduction, finger extension, wrist flexion and extension, elbow flexion and extension, shoulder abduction. Stabilise the joint above the one being tested, give a clear command, and grade honestly:

• 0 — no contraction

• 1 — flicker of contraction

• 2 — movement with gravity eliminated

• 3 — movement against gravity

• 4 — movement against resistance (4-, 4, 4+)

• 5 — normal power

Note the pyramidal pattern in the arm: weak elbow extension, wrist and finger extension and fine finger movements, with relatively preserved antigravity flexors.

4. Reflexes

Biceps (C5-6), supinator (C5-6) and triceps (C7-8). Place the arm relaxed across the abdomen. If a reflex appears absent, use reinforcement — clench the jaw or squeeze the knees together — before declaring it gone. Briskness with spread to adjacent digits is as informative as absence.

5. Coordination

Finger-to-nose with eyes open then closed, watching for dysmetria and intention tremor, then rapid alternating movements. Impersistence or drift adds further localising value.

6. Sensation

Compare distal to proximal and always left with right. Light touch and pinprick first: are the feet also affected (peripheral pattern)? Then joint position sense at the index finger and vibration at the distal radius or styloid with a 128 Hz tuning fork. Dermatomal anchors worth memorising: C6 thumb, C7 middle finger, C8 little finger.

The Lower Limb: Lead With the Gait

Whenever the scenario allows, watch the patient walk first. The gait is the single highest-yield manoeuvre in lower limb neurology and the most frequently skipped.

• Hemiplegic — circumduction, extended knee, equinovarus foot

• Spastic — scissoring, crossing of the legs

• High-stepping with foot slap — common peroneal or peripheral neuropathy

• Waddling — proximal myopathy

• Shuffling with festination and reduced arm swing — Parkinsonism

• Ataxic, broad-based — cerebellar or sensory

1. Inspection

Expose to above the knee. Look for distal wasting (peroneal muscles and tibialis anterior give the inverted champagne-bottle legs of Charcot-Marie-Tooth), pes cavus, clawing of the toes, calf asymmetry, scars and trophic changes.

2. Tone

Roll the leg at the hip, lift the knee abruptly and feel for a spastic catch, then test for ankle clonus. In the lower limb the pyramidal pattern weakens hip flexion and knee flexion, with relatively preserved extension — the exact mirror of the arm.

3. Power

Hip flexion, extension and abduction; knee flexion and extension; ankle dorsiflexion and plantarflexion; foot inversion, eversion and toe extension. Testing dorsiflexion against gravity alone can reveal a subtle foot drop that formal grading hides.

4. Reflexes and plantar response

Knee jerk (L3-4), ankle jerk (S1-2); use the Jendrassk manoeuvre before calling an ankle jerk absent — an absent ankle jerk is a defining sign of peripheral neuropathy. Scrape the lateral sole with a key or orange stick and watch the great toe. Extensor plantars are upper motor neurone until proven otherwise.

5. Coordination

Heel-to-shin, each side, eyes open then closed.

6. Sensation

Light touch and pinprick over the feet then proximal legs; proprioception at the great toe (hallux-first, before the finger); vibration at the medial malleolus. Anchors: L4 medial malleolus, L5 dorsum of the great toe and first webspace, S1 lateral sole. If a cord lesion is suspected, map the sensory level on the trunk and test saddle sensation with consent — and never forget to complete by examining the spine.

Pattern Recognition: The Tables You Must Own

The Seven Cases You Must Be Able to Spot

1. Pyramidal weakness after stroke

Increased tone, pyramidal-pattern weakness, brisk reflexes, clonus and an extensor plantar on one side. Present it as a syndrome, then show whole-patient thinking: I would examine the cardiovascular system, check for carotid bruits, atrial fibrillation and blood pressure, and review imaging.

2. Peripheral sensory-motor neuropathy

Distal symmetrical weakness and wasting, absent ankle jerks, glove-and-stocking sensory loss, maybe trophic foot changes. Your viva answer is the cause list: diabetes, alcohol, B12 deficiency, renal failure, paraproteins, drugs, hereditary. Urine dip, glucose, HbA1c, B12, renal function, serum electrophoresis, and nerve conduction studies form a complete answer.

3. Motor neurone disease

The classic discriminator: mixed upper and lower motor neurone signs with no sensory loss. Wasted, fasciculating hands with brisk reflexes and extensor plantars should make the diagnosis pop into your head instantly. Complete by examining the tongue for fasciculations and assessing speech and swallow, then mention riluzole, non-invasive ventilation and multidisciplinary care.

4. Charcot-Marie-Tooth disease

Pes cavus, claw toes, inverted champagne-bottle calves, distal weakness with foot drop, impaired balance and reduced or absent reflexes. When you see bilateral foot problems with skeletal deformity, always check the spine for scoliosis and ask about family history. Nerve conduction studies separate demyelinating (slow) from axonal (low amplitude) forms.

5. Hereditary spastic paraparesis

Bilateral lower limb upper motor neurone signs — spasticity, brisk reflexes, extensor plantars, scissoring gait — often with pes cavus and minimal weakness, frequently autosomal dominant. It is the great mimic of bilateral cortical or cord disease, and the family history seals it.

6. Old poliomyelitis

Asymmetric lower motor neurone findings in a short, wasted limb with normal sensation and a decades-old history. The absence of sensory loss distinguishes it from neuropathy.

7. Focal mononeuropathies

Short-case favourites: wrist drop (radial), claw hand with a positive Froment sign (ulnar), thenar wasting with positive Phalen or Tinel (median). Test the sensory territories specific to each nerve and know the sites of compression.

Bonus discriminator: Brown-Sequard syndrome — ipsilateral spastic weakness and loss of vibration and proprioception below the level, with contralateral loss of pain and temperature. If you demonstrate dissociated sensory loss and localise it correctly, you have announced yourself as a safe senior candidate.

Presenting Your Findings Like a Registrar

Use a four-step template every single time:

1. Findings — positive and pertinent negative signs

2. Pattern and localisation — name the system and level

3. Summary sentence — a patient with..., most consistent with...

4. Completion — further examination and investigations

Examples:

• Stroke: This patient has a right pyramidal-pattern weakness with spastic tone, brisk reflexes and an extensor plantar, indicating an upper motor neurone lesion of the left hemisphere or brainstem. The most likely cause is cerebrovascular disease. I would examine the cardiovascular system, review neuroimaging and screen vascular risk factors.

• MND: This patient has wasting and fasciculations of the small muscles of both hands with brisk reflexes and extensor plantars but intact sensation — a mixed upper and lower motor neurone picture. My leading diagnosis is motor neurone disease. I would examine the tongue and bulbar function, and arrange neurophysiology to exclude mimics.

• CMT: This patient has bilateral distal lower limb weakness and wasting with pes cavus, clawed toes and absent ankle jerks, in keeping with a hereditary motor sensory neuropathy such as Charcot-Marie-Tooth disease. I would examine the spine and upper limbs, ask about family history, and arrange nerve conduction studies.

Surviving the Viva

Expect questions on localisation, the anatomy of reflex arcs and dermatomes, basic interpretation of nerve conduction studies and EMG, and management priorities such as the diagnostic workup of peripheral neuropathy, multidisciplinary care in motor neurone disease, or urgent imaging in suspected cord compression. Answer in the same pattern-based style: localise first, then investigate, then manage — with safety escalations for red-flag diagnoses.

The Mark-Scheme Killers

• Never skipping the gait, and never forgetting to expose the feet and toes

• Missing fasciculations by not resting and warming the muscles patiently

• Declaring reflexes absent without reinforcement

• Overcalling subtle sensory findings — report what you demonstrably elicited

• Drifting into an endless sensory examination and running out of time

• Presenting a list of findings without a diagnosis — the single most penalised habit

• Falling silent: keep talking to the patient during the examination, since communication is marked in every encounter

A Timing Template That Fits the Station

• 0-1 min: focused history/screen from the scenario while observing the patient

• 1-3 min: inspection, gait where relevant

• 3-6 min: tone and power, both limbs as directed

• 6-8 min: reflexes and plantars

• 8-10 min: coordination and targeted sensation

• 10-12 min: brief patient interaction, closing the consultation safely

• Remaining time: structured presentation, ready for questioning

How to Practise Deliberately

Repetition with real patients beats rereading. Book neurological ward and clinic lists, and run the same ten-minute routine on every willing patient until the sequence is automatic. Film yourself and watch it back — most candidates discover they talk to the ceiling rather than the patient. Pair bedside work with timed mock circuits, and rehearse a two-minute presentation for each of the seven classic cases until you can deliver it under pressure without notes.

Key Takeaways

• Examine to a pattern: upper motor neurone, lower motor neurone, cerebellar, extrapyramidal, plus a sensory map

• The gait is the highest-yield single manoeuvre in lower limb neurology

• Mixed upper and lower motor neurone signs with no sensory loss means motor neurone disease until excluded

• Bilateral foot deformity plus neuropathy means Charcot-Marie-Tooth — check the spine and the family tree

• Always finish with a summary sentence, a diagnosis, and a sensible plan

Master these patterns and the most feared corner of PACES becomes the most predictable. Walk in with a routine you own, present like the registrar you are about to become, and the limb neurology case may be the station that carries your exam.

Good luck — now go examine some feet.