Neurological manifestations of pediatric achondroplasia

Abstract

The neurological and neuroradiological manifestations of pediatric achondroplasia are analyzed on the basis of 10 cases. In addition to the classical symptomatology of an enlarging head, with or without increased intracranial pressure, several patients presented symptoms related to a small foramen magnum. Respiratory problems and quadriparesis were also observed in these patients. Six patients who were treated by foramen magnum decompression showed remarkable improvement. Neuroradiological evaluation revealed a significant number of patients with dilated cortical sulci and basal cisterns, and mild dilatation of the ventricles on computerized tomography (CT) and/or ventriculography. Two patients showed signs of obstruction at the fourth ventricle outlets. Some exhibited anomalous dilatation of cerebral veins and dural sinuses, narrowing of the sinuses at the jugular foramen, and enlarged emissary veins. Ventriculoperitoneal or ventriculoatrial shunts were placed in three patients. In the other children with a large head and dilated ventricles, head growth curves paralleled the normal slope, and there was no significant clinical evidence of increased intracranial pressure or enlarging ventricles on follow-up CT scan.

Neurosurgical implications of achondroplasia

“…6,35 Enlargement of the subarachnoid spaces is commonly seen and is thought also to be a result of the venous hypertension. 41 Rarely is true obstructive hydrocephalus identified, although impairment of fourth ventricle outflow due to a small posterior fossa and a tight CCJ has been postulated to contribute to this phenomenon. 41 A baby with achondroplasia very commonly will have an enlarged head.…”

“…41 Rarely is true obstructive hydrocephalus identified, although impairment of fourth ventricle outflow due to a small posterior fossa and a tight CCJ has been postulated to contribute to this phenomenon. 41 A baby with achondroplasia very commonly will have an enlarged head. Monitoring of head growth should be performed at regular intervals and compared with control charts for children with achondroplasia, because comparison with the typical head growth curve of the general population will lead to unnecessary CSF shunting.…”

“…The proportion of children with achondroplasia who undergo shunt placement varies considerably between centers, ranging from 4.3% in our series, to up to 50%. 2,21,28,29,35,41 In a recently reported pediatric spine surgery series from The JHU, 20% of the 44 patients had undergone shunt insertion. 33 We provide the example of a 6-year-old child with achondroplasia who had moderate ventriculomegaly and a head circumference on the 75th percentile for individuals with the disease, who was not treated with shunt placement, and who remains well and has had a normal developmental outcome to this point (Fig.…”

Lumbar Nerve Root Occupancy in the Foramen in Achondroplasia

“…Achondroplasia is a relatively common genetic disorder with an incidence of one per 13,500 live births and is associated with various abnormalities of the musculoskeletal system, including developmental cervical and lumbar canal stenosis resulting from a postnatal defect in the development of the vertebrae [16]. The cause of a developmentally narrow lumbar canal in patients with achondroplasia is described as a growth disturbance and premature fusion of the posterior elements of the spine [7,14].…”

“…The spinal canal in achondroplasia is narrowed by shortened pedicles and decreased interpedicle distance attributable to a defect in the endochondral ossification leading to early fusion of the pedicles. Numerous studies document reduction in the entire spinal canal area, caudal tapering, and stenosis of the foramina and the effective area for the neural elements [9,14,16,17]. Spinal stenosis is not a problem before late adolescence [6,10], but there may be exceptions [5].…”