Neurological Clinical Examination
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Direct answer
Power, tone, reflexes, coordination and sensation are the five handles of a neurological examination, each mapping onto a defined pathway: corticospinal for power, extrapyramidal and segmental systems for tone, reflex arcs with their segmental roots, cerebellar circuits for coordination, and the dorsal column-spinothalamic pair for sensation. Power is graded 0-5 on the Medical Research Council scale, where grade 3 means movement against gravity only; tendon reflexes are graded 0-4 with 2 normal, and biceps tests C5-6, triceps C7-8, knee L3-4 and ankle S1-2. An upper motor neuron lesion shows hypertonia, hyperreflexia, clonus and an extensor plantar without wasting; a lower motor neuron lesion shows wasting, fasciculations, hypotonia and areflexia. The T4 and T10 dermatomes — nipple and umbilicus — anchor sensory levels on the trunk.
What you must remember
- MRC power grading: 0 no movement, 1 flicker, 2 movement with gravity eliminated, 3 full range against gravity, 4 weak against resistance (subdivided 4-, 4, 4+), 5 normal.
- Reflex roots: biceps and supinator C5-6, triceps C7-8, knee L3-4, ankle S1-2; superficial set — abdominals T8-T12, cremasteric L1-2, plantar S1-2, anal S2-4.
- UMN versus LMN signature: clasp-knife hypertonia, hyperreflexia with clonus, extensor plantar and no marked wasting against flaccidity, wasting, fasciculations and lost reflexes.
- Reflex grading scale: 0 absent, 1 hypoactive, 2 normal, 3 hyperactive without clonus, 4 clonus; the Jendrassik manoeuvre reinforces an absent jerk through gamma bias.
- Sensory dual system: dorsal columns carry vibration, joint position and discriminative touch ipsilaterally; spinothalamic fibres carry pain and temperature, crossing within one to two segments.
- Tone taxonomy: clasp-knife spasticity (pyramidal), lead-pipe and cogwheel rigidity (basal ganglia), hypotonia (LMN or cerebellar).
- Screening anchors: pronator drift for subtle pyramidal weakness, Romberg for sensory ataxia, dermatome landmarks C6 thumb, T4 nipple, T10 umbilicus, L4 medial malleolus, S1 lateral border of foot.
A short case walked through
Take the classic Indian short case: examine the right upper limb of a 55-year-old. Inspection first — attitude of the limb, wasting of thenar or small muscles of the hand, fasciculations under good light. Tone at the wrist and elbow, feeling for the catch and release of spasticity. Power muscle group by group on the MRC scale: shoulder abduction, elbow flexion and extension, wrist and fingers, always comparing with the normal side. Reflexes — biceps, supinator, triceps — graded 0-4, looking for asymmetry rather than absolute scores; then the plantars and a sweep for clonus at ankle, knee and wrist. Sensation in the modalities of both columns, and cortical signs if the lesion is cerebral. A right-sided grade 4 power, brisk reflexes, extensor plantar and absent wasting localises to a left hemisphere lesion — the physiology of crossed corticospinal fibres doing the localising for you.
Where candidates lose marks
Grade 3 is the definition most often fumbled: movement through full range against gravity, with resistance eliminated — many candidates say "against resistance", which is grade 4 territory. Clonus is not the same as a brisk jerk; it is sustained, rhythmic reflex oscillation, five or more beats, and it earns reflex grade 4 on the standard scale. Pronator drift is screened with eyes closed and arms outstretched: a pyramidal weakness lets the affected arm drift down and pronate, while a cerebellar lesion drifts it upward. The viva staple is sensory: pinprick crossing within a segment or two means a spinothalamic lesion hurts on the opposite side below the level — and light touch, carried by both systems, is the least localising modality to rely on.
Frequently asked questions
Which spinal roots are tested by each tendon jerk?
Biceps and supinator jerk C5-6, triceps C7-8, knee jerk L3-4 and ankle jerk S1-2 — a one-line answer that examiners expect verbatim.
How do UMN and LMN lesions differ on examination?
UMN lesions produce hypertonia, hyperreflexia, clonus, an extensor plantar and no significant wasting; LMN lesions produce flaccid tone, wasting, fasciculations and abolished reflexes.
Why does the Jendrassik manoeuvre reinforce an absent reflex?
Clenching the teeth or pulling interlocked hands increases gamma motor neuron drive, pre-loading muscle spindles so the same tendon tap produces a larger afferent volley.
What does an extensor plantar response indicate?
Babinski's sign indicates dysfunction of the corticospinal (pyramidal) pathway above the S1-S2 spinal segment, from spinal cord, brainstem or hemisphere disease.
Which tracts carry vibration sense and pain sense?
Vibration and joint position travel the dorsal columns ipsilaterally; pain and temperature enter the spinothalamic tract and cross to the opposite side within one to two segments.