The neurological complications of achondroplasia.

The genetics of achondroplasia are discussed, and then the clinical features. The respiratory complications are only considered when related to the neurological ones which are the concern of this paper; and their effects on morbidity and mortality. Cervicomedullary compression can cause pain, ataxia, incontinence, apnea, and respiratory arrest. One of the signs can be progressive quadriparesis which can be a presenting symptom; and may be caused by a vascular lesion as well as by cord compression. Also nerve root compression in the neural foramina can cause symptoms and signs in the limbs. Enlargement of the head is a feature of achondroplasia. This may be due to subdural haematoma related to the wide subarachnoid spaces, and to trauma. Hydrocephalus is common, and may be non-communicating and due to aqueduct stenosis, but is much more often communicating and the result of raised intracranial venous pressure. Shunting may be necessary, but surgery directed towards relieving the venous pressure may be more logical. Otitis media often affects these children, and can cause deafness and subsequently delayed language development. Sleep disturbances can be the result of both neurological and respiratory complications. Apart from the treatment for hydrocephalus the most important decision is often the question of operating on the cervical medullary compression. Risk factors such as brisk reflexes, small foramen magnum, and central hypopnea, can be an indication for surgery; but timing can be difficult as the cord compression can resolve spontaneously. The intelligence levels of these children are usually normal, and studies have shown a surprisingly high level of satisfaction with the services provided.