Prematurity is Most Strongly Associated with Periventricular Leukomalacia
Prematurity (Option C) is the most strongly associated factor with periventricular leukomalacia, representing the primary risk factor and underlying pathophysiological mechanism for developing this condition. 1
Understanding the Question Context
This question presents a patient with:
- Scissoring gait (bilateral lower limb spasticity)
- MRI showing periventricular leukomalacia (PVL)
- Asking what is most strongly associated with the diagnosis
The key distinction here is between causation versus consequence—what causes PVL versus what results from it.
Why Prematurity is the Answer
Prematurity is the primary risk factor that leads to PVL development, with the incidence of severe periventricular hemorrhagic infarction reaching 30% in infants born at 22 weeks and decreasing to 3% at 28 weeks gestational age, highlighting the extreme vulnerability of preterm infants. 1
The pathophysiology centers on the premature infant's white matter vulnerability during the critical window of 24 to 34 postconceptional weeks, when premyelinating oligodendrocytes predominate in periventricular regions and are particularly susceptible to hypoxic-ischemic injury. 2
Why the Other Options Are Consequences, Not Causes
Bilateral Lower Limb Spasticity (Option B)
- This is a clinical manifestation of PVL, not the underlying cause. 1
- The scissoring gait pattern is pathognomonic for bilateral lower limb spasticity (spastic diplegia), which results from the motor pathway injury caused by PVL. 3
- Fractional anisotropy within bilateral corticospinal tracts shows significant correlation with motor dysfunction in PVL patients, confirming this is an outcome of the white matter injury. 4
Static Motor Delay (Option A)
- This is an outcome of PVL, representing a broad category that could result from many conditions. 1
- Motor dysfunction develops secondary to descending motor tract injury along with overlying cortical volume reduction. 4
Periventricular White Matter Changes on MRI (Option D)
- This is the radiographic definition of PVL itself, not an associated factor. 5
- While this describes what PVL looks like on imaging (increased signal intensity of periventricular white matter on T2-weighted sequences), it is tautological to say PVL is associated with the MRI findings that define it. 6
Clinical Context and Prognosis
The presence of bilateral cystic PVL on MRI predicts nonambulant cerebral palsy with more severe motor impairment, while noncystic PVL is more likely to result in ambulant cerebral palsy. 3
Importantly, 43% of infants with cystic PVL also have intraventricular hemorrhage (IVH), requiring monitoring for both conditions. 1
The incidence of cerebral palsy in preterm infants has decreased 3-fold from the early 1990s to early 2000s, largely due to a 93% reduction in cystic periventricular leukomalacia, underscoring the central role of prematurity in this condition's epidemiology. 1