Source / episode info

• **Episode:**49
• **Title:**Divine Intervention Episode 49 – 3rd Year Neurology Clerkship Shelf Review Part 6.
• **Published:**2018-09-17
• Source:Episode page

One-liner

This episode reviews high-yield neurological concepts including the differentiation of pupillary light reflexes (PLR), identifying spinal cord lesions via sensory levels, recognizing brainstem syndromes like Wallenberg's, and mastering specific peripheral nerve deficits from C5 to S2.

High-yield summary

• Pupillary Light Reflex (PLR): An Afferent defect (CN II issue) results in a diminished response when shining light into the affected eye; an Efferent defect (CN III issue) results in a failure of constriction upon testing either pupil.
• Sensory Level: A sharp, distinct demarcation of sensory loss across the body suggests a spinal cord lesion (myelopathy).
• Wallenberg Syndrome (Lateral Medullary): Characterized by ipsilateral facial pain/temp loss and contralateral body pain/temp loss; also involves dysphagia and ataxia.
• Peripheral vs. Radicular: A "stocking-glove" distribution of sensory loss points to a peripheral neuropathy, whereas a dermatomal pattern suggests a nerve root (radiculopathy) issue.
• Nerve Injury Patterns: Axillary nerve injury affects shoulder abduction/deltoid; Peroneal nerve injury causes foot drop (loss of dorsiflexion/eversion); Median nerve injury classically presents as Carpal Tunnel Syndrome.
• High Dermatomes: The nipple line is T4, the umbilicus is T10, and the symphysis pubis is T7.

Learning objectives

• Differentiate between afferent and efferent defects of the pupillary light reflex.
• Identify the specific anatomical syndromes associated with brainstem lesions (e.g., Wallenberg).
• Localize spinal cord pathology based on sensory level findings and bowel/bladder function.
• Distinguish between peripheral neuropathy, radiculopathy, and myopathy using pattern recognition.
• Correlate specific motor deficits (e.g., deltoid weakness) with their corresponding peripheral nerves.