Neuroscience Clerkship

 

 

STATIC ENCEPHALOPATHY

 

When a infant or young child presents with motor or cognitive abnormalities, one of the first questions to answer is whether the condition is a static or progressive encephalopathy. Both may involve deficits of language, vision, hearing, and motor function. Likewise, both may result to failure to obtain certain motor and cognitive milestones. The key in the diagnosis of a static encephalopathy is that it has a non-progressive course. Although patients may have delayed motor milestones, they do not lose milestones, as they do in a progressive neurologic disorder.

The differentiation is critical as the differential diagnosis and prognosis are markedly different. A chronic static encephalopathy may be caused by genetic or acquired etiologies. Some may associated anatomical deformations of the brain. Among static encephalopathies, cerebral palsy (CP) is the prototypic disorder. CP is a disorder primarily affecting motor function and tone. Most often, patients with CP have spasticity and other upper motor neuron signs. Some patients will have basal ganglionic dysfunction with dyskineas, chorea or athetosis. The most common form of CP is a spastic diplegia (of the legs) followed by hemiplegic, dyskinetic, ataxic and quadriplegic forms. Children with CP may or may not have intellectual problems or seizures. Indeed, many have above normal intellectual functon.

CP can be caused by both prenatal and perinatal insults. Many times the etiology is unknown. The more common brain abnormalities are intraventricular hemorrhage (IVH) and periventricular leukomalacia (PVL) in premature infants, and perinatal hypoxic ischemic encephalopathy (HIE) in term newborns. Other causes are CP include congenital infections, toxins, maternal infection during pregnancy and labor, and genetic and metabolic disorders.

Conversely, chronic progressive encephalopathies are ususally caused by genetic inborn errors of metabolism (e.g., peroxisomal metabolism or lysosomal storage disorders), leukodystrophies, and rare infections (e.g., HIV, SSPE), among other uncommon conditions.

 

Above: Periventricular leukomalaica, one of the more common MRI findings in patients with CP, especially those who were premature.