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Difficulty: MediumPhysical Examination Findings

Match the following distinct neurological physical examination signs and maneuvers with their most likely underlying pathophysiological mechanism or neuroanatomical lesion location.

  • Lhermitte signDemyelination or compression of the posterior cervical spinal cord
  • Pronator driftMild contralateral pyramidal tract (upper motor neuron) dysfunction
  • Marcus Gunn pupil (relative afferent pupillary defect)Asymmetric optic nerve injury interrupting the afferent limb of the pupillary light reflex
  • Positive Dix-Hallpike maneuverMigration of otoconia into the posterior semicircular canal

Answer

Lhermitte sign correlates with posterior cervical spinal cord pathology. Pronator drift correlates with mild contralateral pyramidal tract dysfunction. Marcus Gunn pupil correlates with asymmetric optic nerve injury. A positive Dix-Hallpike maneuver correlates with migration of otoconia into the posterior semicircular canal.
Each specific physical examination maneuver isolates a unique neuroanatomical pathway. Properly matching the clinical sign to its pathophysiological basis is essential for localizing the lesion and establishing an accurate diagnosis.

Step-by-Step Solution

1
Evaluate Lhermitte sign.
Matched with demyelination or compression of the posterior cervical spinal cord.
Neck flexion stretches the inflamed or demyelinated cervical spinal cord, producing a characteristic shock-like sensation.
2
Evaluate pronator drift.
Matched with mild contralateral pyramidal tract dysfunction.
Upper motor neuron lesions disproportionately weaken supinators of the upper extremity, leading to pronation when visual compensation is removed.
3
Evaluate Marcus Gunn pupil.
Matched with asymmetric optic nerve injury.
The swinging flashlight test reveals a diminished direct pupillary light reflex due to an impaired afferent limb, signifying optic nerve pathology.
4
Evaluate positive Dix-Hallpike maneuver.
Matched with migration of otoconia into the posterior semicircular canal.
The maneuver changes the orientation of the posterior semicircular canal relative to gravity, causing displaced otoconia to move and trigger vertigo and nystagmus.

Key Concept

Neurological physical examination signs are critical for precise neuroanatomical localization and understanding the underlying pathophysiological mechanisms of disease.
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Physical Examination Findings

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