Neurosurgical aspects of childhood hypophosphatasia

Hypophosphatasia (HPP; MIM241510) is a rare inborn error of bone metabolism of recessive inheritance. It is caused by mutations in the gene encoding the tissue-nonspecific alkaline phosphatase. Apart from problems in bone mineralization, growth failure, and premature loss of decidual teeth, the infantile and the childhood types of HPP are associated with premature fusion of cranial sutures. We report on seven children affected with infantile and childhood HPP who presented with craniosynostosis. Neurosurgical intervention was necessary in four of them because of intracranial hypertension. In one of these, severe dural calcification posed an unexpected problem during surgery. Secondary ectopia of the cerebellar tonsils were detected in five of the seven patients and caused hydrosyringomyelia in one of them. Since cranial sutures are frequently involved in infantile and childhood HPP, a multidisciplinary approach for the clinical care is necessary, including long-term neurosurgical surveillance.