DOES HIP DISLOCATION MATTER IN CEREBRAL PALSY?

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influenced by stimulation of the locus coeruleus in the brainstem, a response mediated mainly by the greater superficial petrosal branch of the facial nerve. This response may be triggered by stimulation of the

trigeminal ganglion, predominantly by a brainstem reflex, although the trigeminal nerve itself has a smaller efferent role.21,22 Raskin et alZ3 reported that brainstem electrodes implanted for the suppression of low-back pain sometimes induced ipsilateral headache with many of the features of migraine, occasionally also accompanied by transient fixed visual disturbances. The results of Bonuso and his colleagues,z4 who studied the effects of 2 % nitroglycerine ointment, re-emphasise the importance of scalp blood vessels in migraine attacks. When 5 mg of the ointment was applied to the frontotemporal area in 20 common migraine patients it induced headaches significantly more often than did placebo in migraine patients, or active ointment in 10 control subjects. In subsequent open studies the side of the patient’s usual headache was found to be more sensitive. Headache was much less frequent when the same dose was applied to the wrist, showing that the nitroglycerine was acting locally and not systemically, although the effect could be on nerve endings rather than on vessel diameter per se. Almost all patients had nausea, but none of the 40 common and 3 classical patients in the study had any aura symptoms. These findings suggest that local scalp blood vessels are sensitised to the action of nitroglycerine. However, to account for those patients who have infrequent attacks on the opposite side to the one usually affected, the sensitisation cannot be structural and certainly not cumulative.25 The neurogenic and vascular hypotheses are by no means incompatible; it is possible to reconcile them by proposing a positive feedback loop. Thus, neurogenic release of inflammatory neurotransmitters in and around blood vessels via the facial and trigeminal nerves, perhaps enhanced by the local involvement of platelets, might produce painful vasodilatation perceived by the trigeminal nerve. Part of this response could be mediated by the trigeminal nerve alone, via pathways similar to the axon reflex.26 1. Lauritzen M. Cortical spreading depression as a putative migraine mechanism. Trends Neurosci 1987; 10: 8-13. 2. Barkley GL, Tepley N, Simkins R, Moran JE, Welch KMA. Neuromagnetometer studies of migraine patients. Cephalalgia 1989; 9 (suppl 10): 127-28. 3. Lauritzen M. Regional cerebral blood flow during cortical spreading depression in rat brain: increased reactive hyperperfusion in low-flow states. Acta Neurol Scand 1987; 75: 1-8. 4. Welch KMA, Levine SR, D’Andrea G, Helpern JA. Brain pH in migraine: an in vivo phosphorus-31 magnetic resonance spectroscopy study. Cephalalgia 1988; 8: 273: 76. 5. Parry CH. On the effects of compression of the arteries in various diseases, and particularly in those of the head; with hints towards a new mode of treating nervous disorders. Memoirs Med Soc Lond 1792; 3: 77-113. 6. Drummond PD, Lance JW. Extracranial vascular changes and the source of pain in migraine headache. Ann Neurol 1983; 13: 32-37. 7. Graham JR, Wolff HG. Mechanism of migraine headache and action of ergotamine tartrate. Arch Neurol Psychiatry 1938; 39: 737-63.

HK, Olesen J, Tfelt-Hansen P. Intravenous nitroglycerin as an experimental model of vascular headache: basic characteristics. Pain

8. Iversen

1989; 38: 17-24. H, Lundberg PO, Olsson S. Drug-related headache. Headache 1989; 29: 441-44. 10. Heyck H. Pathogenesis of migraine. Res Clin Stud Headache 1969; 2: 9. Asmark

1-28.

11. Spierings ELH, Saxena PR. Antimigraine drugs and cranial arteriovenous shunting in the cat. Neurology 1980; 30: 696-701. 12. Bickerstaff ER. Complicated migraine. In: Rose FC. Progress in migraine research 2. London: Pitman, 1984: 83-101. 13. Olsen TS, Lassen NA. Blood flow and vascular reactivity during attacks of classical migraine—limitations of the Xe-133 intraarterial technique. Headache 1989; 29: 15-20. 14. Soges LJ, Cacayorin ED, Petro GR, Ramachandran TS. Migraine: evaluation by MR. Am J Neuroradiology 1988; 9; 425-29. 15. Bogousslavsky J, Regli F, Van Melle G, Payot M, Uske A. Migraine stroke. Neurology 1988; 38: 223-27. 16. Peatfield RC, Gawel MJ, Rose FC. Asymmetry of the aura and pain in migraine. J Neurol Neurosurg Psychiatry 1981; 44: 846-48. 17. Mayberg MR, Zervas NT, Moskowitz MA. Trigeminal projections to supratentorial pial and dural blood vessels in cats demonstrated by horseradish peroxidase histochemistry. J Comp Neurol 1984; 223: 46-56. 18. Davis KD, Dostrovsky JO. Activation of trigeminal brain-stem nociceptive neurons by dural artery stimulation. Pain 1986; 25: 395-401. 19. Moskowitz MA, Buzzi MG, Sakas DE, Linnik MD. Pain mechanisms underlying vascular headaches. Rev Neurol 1989; 145: 181-93. 20. Goadsby PJ, Lambert GA, Lance JW. Differential effects on the external carotid circulation of the monkey evoked by locus coeruleus stimulation. Brain Res 1982; 249: 247-54. 21. Lambert GA, Bogduk N, Goadsby PJ, Duckworth JW, Lance JW. Decreased carotid arterial resistance in cats in response to trigeminal stimulation. J Neurosurgery 1984; 61: 307-15. 22. Goadsby PJ, Lambert GA, Lance JW. Stimulation of the trigeminal ganglion increases flow in the extracerebral but not the cerebral circulation of the monkey. Brain Res 1986; 381: 63-67. 23. Raskin NH, Hosobuchi Y, Lamb S. Headache may arise from perturbation of brain. Headache 1987; 27: 416-20. 24. Bonuso S, Marano E, Di Stasio E, Sorge F, Barbieri F, Ullucci EA. Source of pain and primitive dysfunction in migraine: an identical site? J Neurol Neurosurg Psychiatry 1989; 52: 1351-54. 25. Peatfield RC, Bond RA, Rose FC. Do migrainous headaches become more consistently lateralized? Cephalalgia 1987; 7: 73-75. 26. Sakas DE, Moskowitz MA, Wei EP, Kontos HA, Kano M, Ogilvy CS. Trigeminovascular fibers increase blood flow in cortical gray matter by axon reflex-like mechanisms during acute severe hypertension or seizures. Proc Natl Acad Sci USA 1989; 86: 1401-05.

DOES HIP DISLOCATION MATTER IN CEREBRAL PALSY? Patients with severe cerebral palsy, especially those with associated mental handicap, often have gross deformities that deprive them of the last vestiges of their human dignity. Hip and spine deformities in particular can lead to a bed-bound life of total dependence. Successful management of deformity may facilitate sitting, dressing, and toileting and consequently help communication, feeding, social skills, and hand function. Hip instability in cerebral palsy results from adductor and flexor spasticity with subluxation and eventual dislocation of the femoral head, which comes to rest on the posterolateral surface of the ilium. Adductor spasticity is often asymmetrical, leading to the characteristic windswept deformity of the legs with pelvic obliquity. Scoliosis commonly compounds the deformity. Surgical management of subluxed or dislocated hips has been advocated to prevent hip pain, enable sitting,l improve perineal hygiene, and perhaps prevent pelvic obliquity and scoliosis. The operative approach varies from soft-tissue release to the more radical femoral and pelvic osteotomies and occasionally total hip replacement.2 Late results of surgery in these patients are disappointing. A retrospective

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survey2 lately showed no functional benefits 12 years after hip surgery in non-ambulant patients with whole body cerebral palsy and severe mental retardation by comparison with a similar group treated conservatively. Mean age at surgery was 13 years and all patients had dislocation of one or both hips before treatment. Troublesome hip pain occurred in only 4% of untreated cases. In earlier studies, pain from a dislocated hip was reported in 0-50% of patients.3-5 The frequency of scoliosis and hip dislocation depends on the severity of the cerebral palsy. There is little evidence that scoliosis is a consequence of hip dislocation.2,6 Orthotic management may be as successful as surgery in promoting the sitting posture. Surgery for dislocated hips in non-ambulant patients cannot be recommended except perhaps when severe symptoms are not controlled by medical treatment. If late surgery in severe cases does not achieve its aims early prophylactic surgery seems an attractive alternative. Close clinical monitoring and regular radiographs enable diagnosis of hip subluxation in young children with cerebral palsy. The aim of soft-tissue release surgery at this stage is to contain the femoral head and therefore allow normal acetabular development as proposed in congenital hip dislocation.7 Sadly the data available to test this hypothesis are inconclusive. The frequency and natural history of hip dislocation in cerebral palsy depend on the type and severity of the motor disorder and the ability to walk. Although population-based studies of incidence are not available, dislocation of the hip is commonly reported in severe quadriplegic cerebral palsy8 but rarely in patients who can walk independently or in children with hemiplegia or diplegia.6,9Against this background reports of successful prophylactic surgery are impossible to interpret.4,lo As Bleckll commented, "The controversy and confusion concerning prevention of the hip dislocation in cerebral palsy can be resolved only if the data include precisely the functional ambulatory status of the patient and the age". There is a continuing need to study the natural history of the conditions9 and intervention studies must contain a control group. Results of prophylactic surgery are poor in severely involved quadriplegic children, especially if subluxation or dislocation occur early in life .4,10,12 Since the unstable hip does not necessarily cause functional complications to many such patients, early surgery like late surgery has no proven value. Children with the potential for independent ambulation should be carefully monitored clinically and radiographically. Those who walk independently are unlikely to get hip problems, but what should one do about those who will walk late or walk with aids if hip subluxation shows signs of progressing? Surgery may be very successful in such patients/,12 but careful case selection, perhaps with gait analysis and vigorous postoperative therapy, 12 are

indispensable. MM, Abraham E, Nickel VL. Salvage surgery of the hip to improve sitting posture of mentally retarded severely disabled children with cerebral palsy. Dev Med Child Neurol 1972; 14: 51-55. Pritchet JW. Treated and untreated unstable hips in severe cerebral palsy.

1. Hoffer

2.

Dev Med Child Neurol 1990; 32: 3-6. 3. Moreau M, Drummond DS, Rogala E, Ashworth A, Porter P. Natural history of the dislocated hip in spastic cerebral palsy. Dev Med Child Neurol 1979; 21: 749-53. 4. Kalen V, Bleck EE. Prevention of spastic paralytic dislocation of the hip. Dev Med Child Neurol 1985; 27: 17-24. 5. Feldkamp M. Late results of hip and knee surgery in severely handicapped cerebral palsy patients. Arch Orthop Traum Surg 1982; 100: 217-24. 6. Cooke PH, Cole WG, Carey RPL. Dislocation of the hip in cerebral

palsy—natural history and predictability. J Bone Joint Surg 1989; 71B: 441-46. 7. Sherlock DA, Gibson PH, Benson MKD. Congenital subluxation of the hip: a long term review. J Bone Joint Surg 1985; 67B: 390-98. 8. Samilson RL, Tsou P, Aamoth G, Green WM. Dislocation and subluxation of the hip in cerebral palsy. J Bone Joint Surg 1972; 54A: 863-73. 9. Howard CB, McKibbin B, Williams LA, Mackie I. Factors affecting the incidence of hip dislocation in cerebral palsy. Bone J Joint Surg 1985; 67B: 530-32. 10. Sharrard WJW, Allen JMH, Heaney SH. Surgical prophylaxis of subluxation and dislocation of the hip in cerebral palsy. J Bone Joint Surg 1975; 57B: 160-66. 11. Bleck EE. Orthopaedic management in cerebral palsy. Clin Dev Med 1987; no 99-100. 12. Banks HH, Gren WJ. Adductor myotomy and obturator neurectomy for the correction of adduction contracture of the hip in cerebral palsy. J Bone Joint Surg 1960; 42A: 111-26.

MEDICAL INFORMATICS Medical informatics, according to two US researchers,1 "is emerging as a distinct academic entity". More cynically one could say that the academic world has realised that grants are to be had, jobs created, and money made from building databases of medical information. Commerce has already thought of this possibility, but will welcome the cachet of respectability bestowed by association with academics, the free training in the subject given to potential employees by academic institutions, and the cheap input of data (the most tedious part of information storage/retrieval) by academics looking for kudos. The bandwagon is about to roll, and there is a rush to climb aboard. For those not yet literate in this field, Greenes and Shortliffel point out that the name informatics has been anglicised from the French informatique, for which there is no English equivalent; whether this will please those in France who oppose the use of "franglais" remains to be seen. We learn from the US workers that "Medical Informatics is the field concerned with the cognitive, information processing, and communication tasks of medical practice, education and research, including the information science and technology to support these tasks. The methodologies for processing and communication of information may be viewed as both a science and a technology. This duality of information processing, in which computers are viewed as a tool for the science and as a vehicle for the technology, is connoted by the French term informatique". So, the storage of medical information in the form of computerised databases makes it possible to retrieve the information quickly, transmit it around the world (or even bounce it off the moon if so desired), sort it by various criteria, and display it in easily assimilable format. This is hardly news. The main reason that the predicted explosion in the use of computerised data has not yet happened is that few medical people can be bothered to learn how to use computers, and even the prospect of entering all the existing information, let alone new material, is daunting. The advent of the personal computer gave us all the opportunity to become computer literate, and thus to liberate ourselves from the tyranny of computer professionals. Few of us grasped this opportunity at the time, and computer technology has subsequently advanced at such a pace that the amateur has difficulty in keeping up. The professionals are back in power, and will once again control our access to computerised information. Although doctors may thump the keyboards, professionally prepared software packages will control how we use data, and the data available to us will be controlled by those who (selectively)