Question

A child with a history of delayed cry at birth presents with spasticity and weakness of the lower limbs, but can use his hands to feed himself. What is the most likely site of lesion?

• A. Cerebral cortex – periventricular leukomalacia
• B. Brachial plexus
• C. Spinal cord – cervical region
• D. Basal ganglia

Hint:

Neuropathology of Cerebral Palsy Subtypes:
$\bullet$ Spastic Diplegia (Legs $>$ Arms) $\rightarrow$ Periventricular Leukomalacia (PVL) (preterm watershed zone).
$\bullet$ Spastic Hemiplegia $\rightarrow$ Unilateral middle cerebral artery stroke cortical injury.
$\bullet$ Dyskinetic CP $\rightarrow$ Basal ganglia Thalamic injury (acute term HIE Kernicterus).

Answer 1

The Correct Option is A

Concept:
Cerebral palsy (CP) is a group of permanent disorders of movement and posture attributed to non-progressive disturbances occurring in the developing fetal or infant brain.
The clinical subtype and neurological distribution of motor deficits correspond directly to the specific anatomical location and timing of the underlying neuropathology.
Explanation:
• The child exhibits Spastic Diplegia, characterized by bilateral lower-limb spasticity, scissoring gait, hyperreflexia, and motor weakness, with relative sparing or mild involvement of the upper extremities (enabling purposeful hand use like self-feeding).

• The neuropathological hallmark of spastic diplegic cerebral palsy is Periventricular Leukomalacia (PVL), which predominantly affects the periventricular white matter adjacent to the lateral ventricles.

• In the somatotopic organization (homunculus) of the descending corticospinal motor radiation passing through the internal capsule, the axons originating from the motor cortex destined for the lower extremities (legs) course immediately adjacent to the lateral ventricular borders.

• The descending fibers supplying the upper extremities (arms and hands) are situated more laterally and peripherally, away from the vulnerable periventricular watershed zone, and are thus spared in focal periventricular necrotic lesions.

• Basal ganglia lesions (dyskinetic/athetoid CP) result from acute profound asphyxia/hypoxic-ischemic encephalopathy in term infants, causing involuntary movements, choreoathetosis, and dystonia.
Final Answer:
Spastic diplegia with predominant lower-limb motor impairment results from periventricular leukomalacia (PVL) affecting the medial corticospinal motor tracks in the periventricular white matter.