Abstract
Purpose:
Hypophosphatasia (HPP) is a rare disease caused by reduced activity of alkaline phosphatase (ALP), and is secondary to mutations in ALPL, the gene encoding tissue-nonspecific ALP (TNSALP). There are at least six clinical forms and the spectrum of disease is wide, ranging from stillbirth to pathologic fractures in adulthood. Craniosynostosis and papilledema may accompany the infantile and childhood forms. There are six reported cases of craniosynostosis and papilledema in HPP; however, none contain ophthalmic follow-up. We report our experience with three patients with infantile HPP, craniosynostosis, and papilledema.
Methods:
Patients received comprehensive ophthalmic examination and follow-up while receiving treatment for complications of infantile HPP.
Results:
A 5.5 month old girl was diagnosed with HPP (compound heterozygote: c.1327G>T, p.Ala443Ser; c.1471G>A, p.Gly491Arg), and with craniosynostosis at six months of age. On ophthalmic examination, 3+ papilledema was found. Two and a half months after cranial vault expansion, papilledema worsened, and a second cranial vault expansion was performed. Four months after the second procedure, the papilledema had resolved and the nerves were pink and healthy with normal visual behavior for age. There has been no recurrence 7 months postoperatively. A 27 month old male was referred for management of complications of HPP (homozygous c.293C>T, p.S98F). Craniosynostosis was found on clinical and radiologic examination and ophthalmologic consultation showed 2+ disc swelling bilaterally; cranial vault expansion was performed. Disc swelling resolved after 4.5 months, and 14 months after cranial vault expansion, the nerves remain pink and healthy with normal visual behavior. His sister (same mutation) was referred at 5.5 years. Infantile HPP was diagnosed at 8 months and nystagmus was noted at 3.5 years. On examination, she had craniosynostosis, bilateral optic atrophy, roving nystagmus, and left exotropia. A cranial vault expansion was performed. At 6.5 years old, acuity was 20/250 OD and hand motions OS, a red green color vision defect, and constricted fields. The nerves remain atrophic.
Conclusions:
Untreated papilledema resulted in visual impairment, but prompt treatment of elevated intracranial pressure associated with craniosynostosis in HPP leads to resolution of papilledema over several months’ time.