The relationship of cerebral palsy subtype and functional motor impairment: a population-based study.

AIM: Traditionally, cerebral palsy (CP) had been classified according to the distribution and quality of motor impairment. A standardized functional classification of gross motor skills has recently been validated - the Gross Motor Function Classification System (GMFCS). The relationship between the neurological subtype of CP and GMFCS level remains undefined in CP.

METHOD: The Quebec Cerebral Palsy Registry (Registre de la paralysie cérébrale au Québec [REPACQ]) over a 4-year birth interval (1999-2002 inclusive) identified 301 children with CP. Information on both CP subtype and GMFCS level was available for 243 children (138 males, 105 females) with final data extraction at a mean age of 44 months (SD 14mo, range 24-79mo). Proportions of children with a particular CP subtype at GMFCS levels I to III versus levels IV to V were determined and compared.

RESULTS: CP subtype versus GMFCS levels I to III or IV to V was distributed proportionally as follows: spastic diplegic, 51/52 (98%) versus 1/52 (2%); spastic quadriparetic, 20/85 (24%) versus 65/85 (76%); spastic hemiplegic, 76/77 (99%) versus 1/77 (1%); dyskinetic, 4/16 (25%) versus 12/16 (75%); other (triplegic or ataxic-hypotonic), 10/13 (77%) versus 3/13 (23%). These distributions (proportions) all yielded significant (p<0.001) Pearson chi(2) values.

INTERPRETATION: Neurological subtype is a powerful predictor of functional status related to ambulation. This has implications for counseling families.