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 cerebrale au Quebec [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 KH2 values. Interpretation Neurological subtype is a powerful predictor of functional status related to ambulation. This has implications for counseling families.