The neurologic complications of Paget's disease.

Paget's disease of bone is associated with involvement of the central and peripheral nervous system. The brain, spinal cord, cauda equina, spinal roots, and cranial nerves can be affected in Paget's disease due to their anatomic relationship to bone. Neurologic syndromes are uncommon but include headache, dementia, brain stem and cerebellar dysfunction, cranial neuropathies, myelopathy, cauda equina syndrome, and radiculopathies. The central complications result from pagetic involvement of the skull. Expansion of diseased bone can result in compression of cranial nerves as they exit their bony foramina. Softening of the skull leads to basilar invagination with compression of the brain stem, cerebellum, and lower cranial nerves. Brain stem compression can cause hydrocephalus. Rarely, there is direct compression of the brain from acute epidural hematoma or hypertrophy of the calvarium. Myelopathy, cauda equina syndrome, and radiculopathies most commonly result from hypertrophy of the spine with direct compression. Spinal stenosis can also result from ossification of extradural structures or pathologic fractures. Ischemia from vascular compression or a steal syndrome has also been described. Neurologic complications rarely occur due to sarcomatous transformation of pagetic bone. Magnetic resonance imaging (MRI), computerized tomography (CT)-myelography, and bone X-rays are helpful to localize the lesion and direct therapy. Treatment options include surgical decompression, ventricular shunt placement, and medical management with calcitonin and/or the bisphosphonates. The selection of treatment will vary depending upon the rate of progression and the severity of the neurologic deficit.