SUMMARY Spinal cord potentials produced by high voltage electrical stimulation of the scalp over the motor cortex were recorded intraoperatively from bipolar electrodes inserted into the epidural space of eleven patients undergoing corrective surgery for scoliosis. Responses to single stimuli could be recorded from the cord at all levels from cervical to low thoracic regions. The potentials were larger in the cervical than in the thoracic region and sometimes were followed by later waves at high stimulation intensities. Conduction velocity in large corticomotoneuron fibres was estimated to be between 50-74ms-1in different patients. This technique for monitoring motor tract function may be a useful adjunct to conventional monitoring of the sensory pathways during surgery.Corrective operations on the spinal column for scoliosis carry a risk of serious neurological damage. This is quite small during Harrington rod instrumentation (04%), but is substantially higher during anterior approaches to the column such as the Zielke operation

We reviewed 47 patients with neurofibromatosis and dystrophic spinal deformities; 32 of these patients had been untreated for an average of 3.6 years and in them the natural history was studied. The commonest pattern of deformity at the time of presentation was a short angular thoracic scoliosis, but with progression the angle of kyphosis also increased. Deterioration during childhood was usual but its rate was variable. Severe dystrophic changes in the apical vertebrae and in particular anterior scalloping have a poor prognosis for deterioration. The dystrophic spinal deformity of neurofibromatosis requires early surgical stabilisation which should be by combined anterior and posterior fusion if there is an abnormal angle of kyphosis or severely dystrophic apical vertebrae. Some carefully selected patients can be treated by posterior fusion and instrumentation alone.

We have evaluated the use of a synthetic porous ceramic (Triosite) as a substitute for bone graft in posterior spinal fusion for idiopathic scoliosis. In a prospective, randomised study 341 patients at five hospitals in the UK and France were randomly allocated either to autograft from the iliac crest or rib segments (171) or to receive Triosite blocks (170). All patients were assessed after operation and at 3, 6, 12 and 18 months. The two groups were similar with regard to all demographic and baseline variables, but the 184 treated in France (54%) had Cotrel-Dubouset instrumentation and the 157 treated in the UK usually had Harrington-Luque implants. In the Triosite group the average Cobb angle of the upper curve was 56 degrees, corrected to 24 degrees (57%). At 18 months, the average was 26 degrees (3% loss). In the autograft group the average preoperative upper curve of 53 degrees was corrected to 21 degrees (60%). At 18 months the mean curve was 25 degrees (8% loss). Pain levels after operation were similar in the two groups, being mild in most cases. In the Triosite group only three patients had problems of wound healing, but in the autograft group, 14 patients had delayed healing, infection or haematoma in the spinal wound. In addition, 15 autograft patients had pain at the donor site at three months. Seven had infections, two had haematoma and four had delayed healing. The haematological and serum biochemistry results showed no abnormal trends and no significant differences between the groups. There were no adverse events related to the graft material and no evidence of allergenicity. Our results suggest that Triosite synthetic porous ceramic is a safe and effective substitute for autograft in these patients. Histological findings on biopsy indicate that Triosite provides a favourable scaffolding for the formation of new bone and is gradually incorporated into the fusion mass.

The British Isles Survey for Rett Syndrome stores longitudinal health data from clinical examinations and postal questionnaires to monitor health and severity in Rett syndrome, including the presence and severity of scoliosis and the effects of corrective surgery. Scoliosis is rarely present at birth (3% before regression) but usually appears by 25 years (87%). The degree tends to increase with growth and by 16 to 20 years, 43% (75 of 173) of cases with classic Rett syndrome reported severe or operated scoliosis. Surgical correction was reported in 91 classic cases. Following initial postoperative recovery, families considered that the operation had improved general well-being for 84% of individuals (42 of 50 classic cases with postoperative health reports). Thirteen of 50 patients walked independently before surgery, and 12 patients did so following surgery; 2 stopped walking, and 1 who had not walked began to do so. Scoliosis surgery usually benefited sitting posture (82% better, 10% worse), chest episodes (52% better, 6% worse), and digestion of food (42% better, 6% worse). However, toilet function was improved in only 10% and deteriorated in 20%. Families reported short-term problems at operation in 48% (24 of 50) and minor recurrence of scoliosis in 22% (11 of 50). Surgery in a specialized unit is satisfactory management for severe scoliosis in Rett syndrome. Recommendations include planning for surgery when the curve passes 40 degrees, ensuring optimal nutrition before and after surgery, robust fixture of the whole spine in two stages, familiarization of the surgical team with the individual and the disorder before the operation, and inclusion of the main carer in the hospital care team. Parents form an important part of the management team. Families also require support during and after this stressful major procedure.

The aetiology of idiopathic scoliosis: biomechanical and neuromuscular factors small curve develops due to a small defect in the neuromuscular control system and a second stage during adolescent growth in which the scoliotic curve is exacerbated by biomechanical factors.