Lower Limb Neurological Examination OSCE — Complete Mark-Scheme Guide

Why This Station Is Tested

Lower limb neurology appears in almost every UK medical school finals OSCE bank. Examiners use it to assess your ability to distinguish upper motor neurone (UMN) from lower motor neurone (LMN) pathology, localise lesions, and present findings coherently. Common scenarios include stroke, multiple sclerosis, spinal cord compression, peripheral neuropathy, and motor neurone disease.

Before You Begin

Introduce yourself, confirm patient identity, explain the examination, and obtain consent. Ask if there is any pain anywhere in the legs before touching. Position the patient lying flat on the couch with legs exposed to the groin. Have a tendon hammer, neurotip/Neurotip, cotton wool, tuning fork (128 Hz), and a key visible on your tray.

Systematic Examination Framework

Inspection

Observe for muscle wasting (LMN), fasciculations (LMN — especially MND), foot drop, pes cavus (hereditary neuropathy), skin changes, scars, or asymmetry. Look for spastic posturing (UMN).

Tone

Roll each leg on the couch and perform a rapid knee lift — UMN lesions produce spasticity (velocity-dependent resistance, clasp-knife phenomenon); LMN lesions produce flaccidity. Also test for clonus at the ankle by rapidly dorsiflexing the foot — sustained clonus (>3 beats) is UMN.

Power — MRC Grading

Test in a logical myotomal order: hip flexion (L1/2), hip extension (L4/5/S1), knee flexion (L5/S1), knee extension (L3/4), ankle dorsiflexion (L4/5), ankle plantarflexion (S1/2), great toe extension (L5 — extensor hallucis longus).

Reflexes

Reinforce with Jendrassik manoeuvre (patient hooks fingers and pulls apart) if reflexes appear absent.

Coordination

Heel-shin test: patient places heel on opposite knee and slides down the shin to the ankle, then back up — cerebellar disease produces an ataxic, wobbling movement. Dysdiadochokinesia is tested in the upper limb, but foot tapping can screen lower-limb cerebellar function.

Sensation

Test in a dermatomal sequence. Modalities to test: light touch (cotton wool — dorsal column/spinothalamic), pinprick (neurotip — spinothalamic), vibration (128 Hz tuning fork at great toe then medial malleolus — dorsal column), proprioception (hold sides of great toe, move up/down with eyes closed — dorsal column). Always compare left to right.

Romberg's Test

Patient stands with feet together and eyes open — if stable, ask them to close their eyes. A positive Romberg (loss of balance with eyes closed but not open) indicates dorsal column or vestibular dysfunction, not cerebellar disease (cerebellar patients are unsteady with eyes open too).

UMN vs LMN — Key Differentials

Common UMN causes: stroke, MS, spinal cord compression, cerebral palsy, MND (UMN component). Common LMN causes: peripheral neuropathy, nerve root compression, Guillain-Barré, MND (LMN component), polio.

Completing the Examination

Offer to examine: gait (including heel-toe walking for cerebellar), upper limbs, cranial nerves, and cerebellar function. Offer to check bladder and bowel function if cord pathology suspected. Present findings systematically: "On examination of the lower limbs, tone was increased bilaterally with brisk knee and ankle reflexes and extensor plantar responses bilaterally, consistent with a bilateral UMN lesion above the level of L1."

Common Mistakes

• Testing power before tone (tone should come first)
• Forgetting to reinforce reflexes — absent reflexes without reinforcement is incomplete
• Missing clonus
• Describing Babinski as "positive" without saying what you saw — say "extensor plantar response"
• Failing to compare sides systematically

Frequently Asked Questions

"What is the difference between spasticity and rigidity and why does it matter in the OSCE?"

Spasticity is a velocity-dependent increase in muscle tone that produces a clasp-knife phenomenon — resistance is maximal at the start of movement then suddenly gives way. It is caused by UMN lesions (stroke, MS, spinal cord compression) and is predominantly in flexors of the arm and extensors of the leg. Rigidity is a velocity-independent increase in tone that is equal throughout the range of movement (lead-pipe rigidity) or has a superimposed tremor (cogwheel rigidity); it is caused by basal ganglia pathology, most commonly Parkinson's disease. In the OSCE, distinguishing these is important because they point to different anatomical lesions: spasticity → cortex or corticospinal tract; rigidity → basal ganglia/extrapyramidal system. Examiners will credit you for demonstrating the velocity-dependent test by varying the speed of your passive movement.

"How do I grade reflexes and what should I say to the examiner?"

Reflexes are graded on a 0–4+ scale: 0 = absent even with reinforcement; 1+ = present only with reinforcement (hypo-reflexic); 2+ = normal; 3+ = brisk without clonus; 4+ = very brisk with clonus. In practice, the most useful clinical distinction is absent, diminished, normal, or brisk. When presenting to the examiner, say something like: "Knee reflexes are brisk bilaterally at 3+, ankle reflexes are brisk bilaterally, and there is sustained ankle clonus on the right — this is consistent with an UMN lesion." Avoid just saying "reflexes present" — quantify and compare sides. Always use the Jendrassik manoeuvre before calling a reflex absent: ask the patient to hook their fingers and pull firmly apart immediately before you strike.

"What does the heel-shin test specifically assess and what does a positive test look like?"

The heel-shin test assesses ipsilateral cerebellar hemisphere function, specifically the coordination of lower limb movement. The patient places the heel of one foot on the opposite knee, then slides it smoothly down the shin to the ankle and back. A positive (abnormal) test shows dysmetria — the heel deviates off the shin, wobbles, or overshoots. This is distinct from weakness or sensory loss, which can also disrupt the test but in a different pattern. In cerebellar ataxia, the movement is irregular and tremulous. When reporting, say: "Heel-shin test is impaired on the left with dysmetric, ataxic movement off the shin, suggesting left cerebellar hemisphere dysfunction." Cerebellar signs are ipsilateral to the lesion, unlike UMN signs which are usually contralateral.

"When is Romberg's test positive and what does it mean clinically?"

Romberg's test is positive when the patient is stable with eyes open but becomes unsteady or falls when they close their eyes. This indicates that the patient is compensating for a loss of proprioceptive or vestibular input by relying on visual feedback. A positive Romberg occurs in dorsal column lesions (e.g., subacute combined degeneration of the cord from B12 deficiency, tabes dorsalis from syphilis), severe peripheral neuropathy, or vestibular disease. It does NOT indicate cerebellar disease — cerebellar patients are unsteady regardless of eye position. In the OSCE, always perform Romberg's at the end of the examination and stand close to the patient for safety. A useful phrase: "Romberg's is positive — the patient maintains balance with eyes open but becomes markedly unsteady on eye closure, suggesting dorsal column or vestibular dysfunction."

"What are the key differences between L4, L5, and S1 nerve root compression?"

L4 compression (e.g., L3/4 disc prolapse) causes: weakness of knee extension and ankle dorsiflexion, reduced or absent knee jerk, sensory loss over the medial shin and foot. L5 compression (L4/5 disc — most common) causes: weakness of ankle dorsiflexion (foot drop) and great toe extension (extensor hallucis longus — a classic L5 test), no reflex change (L5 has no reliable reflex), sensory loss over the lateral shin and dorsum of the foot. S1 compression (L5/S1 disc) causes: weakness of ankle plantarflexion (patient cannot stand on tiptoe on affected side), reduced or absent ankle jerk (most reliable reflex change), sensory loss over the lateral foot and little toe. Remember the mnemonic: L4 = knee jerk, S1 = ankle jerk, L5 = no jerk (no reliable monosynaptic reflex).

"How should I present my lower limb neurological findings to the examiner?"

Present in a logical, systematic order mirroring your examination: inspection, tone, power, reflexes, coordination, sensation, then special tests. Use a structured summary statement at the end. For example: "On examination, there was no wasting or fasciculation. Tone was increased in the right leg with a velocity-dependent, clasp-knife quality. Power was 4/5 throughout the right lower limb. Reflexes were brisk on the right with an extensor plantar response. Coordination was intact bilaterally. Sensation was reduced to all modalities below the right knee. These findings are consistent with a right-sided UMN lesion, most likely at a cortical or subcortical level, and in the context of the acute onset, a right MCA territory stroke should be considered." This structure — findings, then interpretation, then differential — is what examiners are marking.

Related guides: Neurological Examination OSCE · Upper Limb Neurological Examination OSCE · Cerebellar Examination OSCE · Gait Assessment OSCE · Cranial Nerve Examination OSCE