Osteopetrosis with Arnold Chiari malformation type I and brain stem compression.

Osteopetrosis is a collective term for a range of sclerosing bone diseases resulting from an absence or defective function of osteoclasts. The clinical expression is variable and includes skeletal, hematological and neurological manifestations. The common neurological manifestation includes cranial neuropathies involving optic, cochlear, facial and trigeminal nerves. Spastic quadriplegia occurring as a result of brain stem compression in osteopetrosis is uncommon. The association of Type 1 Arnold Chiari malformation with osteopetrosis resulting in brain stem compression syndrome is an extremely rare entity.