Drug may improve bone density in cerebral palsy
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Low doses of pamidronate increase bone mineral density (BMD) in children with spastic cerebral palsy with severe movement impairment, according to results of a preliminary study reported in Developmental Medicine and Child Neurology.
All of the children had spastic quadriplegia, a severe form of cerebral palsy characterized by muscle stiffness in all four limbs, the trunk and often the mouth and tongue. These patients often have mental retardation and other problems. The decreased mobility seen in these children leads to bone loss, which puts them at high risk for fractures.
Previous studies have shown that pamidronate, sold in the U.S. and Canada as Aredia, may benefit children with disabilities and bone thinning. However, these children run the risk of developing low calcium levels in the blood, also referred to as hypocalcemia, if dosages are based on the usual adult treatment. In one study, hypocalcemia occurred in 77 percent of the patients.
Dr. Horacio Plotkin, from the University of Nebraska Medical Center in Omaha, and his associates studied 23 children with severe cerebral palsy and were unable to walk. At the beginning of the study, the patients’ bone mineral density in the lower spine and hip was well below the normal level for their age.
Pamidronate, which is given intravenously, was administered every 4 months, starting with a low dose to minimize any severe drug reactions. The dosage was gradually increased to a maximum dose of 45 milligrams per day for 2 days every 16 weeks. Acetaminophen was given every 6 hours during each infusion cycle to prevent fever and seizures.
After 1 year, the researchers observed significant increases in the bone mineral density of the lower spine and hipbone.
Nine children had at least one fracture and up to five fractures prior to the study. Only one fracture occurred during the 12-month treatment period and the average annual fracture rate fell from 0.98 to 0.004 per year.
Levels of calcium, phosphorus, magnesium, vitamin D, complete blood count, measurements of kidney function, and other metabolic markers, remained stable drug the study period. After 3 percent of the treatment cycles, hypocalcemia without symptoms occurred.
The authors note that ideal dosage and time to begin treatment will be established only after larger trials are conducted.
In an accompanying commentary, Dr. Richard Henderson writes: “One should seriously question whether existing data justify this treatment to prevent fractures in a child who has not, and may never, sustain a fracture.”
On the other hand, he recognizes that physicians may not want to wait for a fracture to occur when a child has profound disabilities and a high risk for fracture.
SOURCE: Developmental Medicine and Child Neurology, September 2006.
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