Case: Anticonvulsant-Induced Rickets
Reported by Andrew Porter
L.D., a 14 year old male with severe mental retardation and epilepsy, was referred for consideration of scoliosis.
The curve was found to be minimal but examination showed deformity of the right wrist. Xray revealed features diagnositic of rickets. An Xray of his left wrist taken 5 years previously was normal. A history of medication with phenytoin and phenobarbitone was elicited from his care-givers. He was placed on vitamin D supplementation.
On follow up, the rachitic changes in his wrist have significantly improved.
Left wrist, 1994
Right wrist, March 1999
Right wrist, June 1999
Right wrist, October 1999
FROM: Myles Clough
As an orthopaedic surgeon, I thought that this case was extremely rare as we come across this type of problem so infrequently. However, reviewing the literature for this site suggested a very different picture. High incidences of rickets (around 4%) were reported in institutionalized epileptic children and numerous studies suggested that abnormalities of vitamin D metabolism are present throughout that population. Increased risk factors appear to include non-ambulatory status, poor diet and lack of exposure to sunlight - all presumably correlated with the severity of mental retardation. Various papers suggest that vit D supplements should be routinely offered to the population of mentally retarded, epileptic, poorly ambulant children. Osteomalacia in the older institutionalized epileptic patient is also common.
There is little in the orthopaedic literature but a study by Lee et al in Detroit shows that pathological fractures in this population are common. They suggest that vitamin D levels should be measured in all such children with fractures and that non-accidental injury should be ruled out where the vitamin D level is normal!
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