Biomedical subjects
Publications and source records attributed to R D Hayward.
A combined radiological and surgical technique that permits identification of appropriate recipient vessels and accurate placement of the atrial catheter in ventriculoatrial shunts is described. The procedure uses readily available radiological skills and reduces operation time and morbidity related to malpositioning of the distal catheter.
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The authors describe the clinical, radiological, and postmortem findings of a case of cloverleaf skull syndrome. The presence of hindbrain herniation, abnormal cervical segmentation, and atlantoaxial subluxation illustrate the anatomical complexity of the skull base and the craniocervical junction that may coexist in this condition. Unavoidable division of occipital emissary veins during elevation of the skin flap at the time of vault remodeling surgery led to an acute and, ultimately, fatal rise in intracranial pressure. Postmortem examination and review of magnetic resonance imaging revealed an anomalous pattern of venous drainage of the intracranial structures that appeared to have developed in response to venous obstruction, secondary to intraosseous venous sinuses and stenosis of the jugular foramina. The relationship between venous hypertension, hindbrain herniation, and hydrocephalus in this situation is reviewed, and the implications for evaluation and management of this vexing disorder are discussed.
Children with growth failure, whether secondary to an endocrinopathy such as growth hormone deficiency or secondary to neurological handicap with poor nutrient intake, grow at a subnormal rate but it is most unusual for a child to have complete growth arrest.
In an attempt to prevent tethering following intradural procedures in the spine or at the foramen magnum silastic film has been inserted as a dural substitute. Magnetic resonance imaging has enabled us to judge the effectiveness of this material in preventing tethering at the operative site. Our experience of Silastic dura substitute in 43 paediatric and adult cases is discussed, and illustrated together with a description of the technique of insertion and an analysis of the complications associated with its use.
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Forty-seven out of 49 patients with a histologically-proven diagnosis of medulloblastoma admitted to our institution between 1 January 1984 and 13 December 1990 were examined post-operatively using either myelography or gadolinium-enhanced magnetic resonance imaging in an attempt to detect clinically occult spinal metastatic disease. Spinal spread of the tumour was identified in nine (19%) patients. Of the 16 patients for whom a 5-year follow-up has been available 12 had no myelographic evidence of spinal disease and of these 10 (83%) remain disease-free. Of the six who have died during this period four had evidence of spinal metastases at presentation. Of all the children in the series with spinal spread identified at the time of their initial hospitalization, only one survives to date (15 months after diagnosis). The remainder had an average life expectancy of 18 months.
The aim of this study was to find reasons for the high incidence of cerebrospinal fluid shunt infections seen in neonates. Four-hundred sixty-six consecutive shunt operations were analyzed retrospectively in 294 children, and 60 children were studied prospectively by quantitative sampling of skin bacteria before surgery and by sampling open wounds, shunt catheters, surgical gloves, and airborne bacteria. In total, 110 strains of coagulase-negative Staphylococcus isolated from the skin of 53 children before surgery were then tested for bacterial adherence. Retrospectively, the infection rate for infants younger than 6 months old was 15.7% (28 of 178 procedures), compared with 5.6% (16 of 288 procedures) for older children (p = 0.0005). Of all infections, 67% were due to coagulase-negative Staphylococcus. Age was the only major factor influencing the infection rate. Three of the 60 children studied prospectively developed postoperative shunt infections. All were younger than 6 months and all had high skin bacterial densities before surgery. Contamination during surgery was generally low, but correlated with the preoperative skin bacterial density. Strains of coagulase-negative Staphylococcus with high bacterial adherence were more commonly found in neonates than in older children. High skin bacterial density in neonates before surgery was a risk factor for infection in this study. These results also suggest that there is selection of more virulent strains of coagulase-negative Staphylococcus on the skin of neonates. Prevention of shunt infections in this high-risk group could be facilitated by the reduction of skin bacterial density before surgery using chlorhexidine shampoos and by the elimination of contamination by skin bacteria during surgery using packs soaked in an antiseptic agent to isolate wound edges and glove-changing before handling the shunt.
Doppler ultrasound studies have demonstrated a raised Gosling pulsatility and Pourcelot resistance index in untreated hydrocephalus. The application of transcranial Doppler ultrasound to the diagnosis of blocked ventriculoperitoneal shunts was studied by comparing the Gosling pulsatility indices of 63 children with symptoms of shunt malfunction with a reference range derived from 248 asymptomatic shunted children. An abnormally raised pulsatility index predicted a blocked shunt with a sensitivity of 56% and a specificity of 97%. The pulsatility index correlated with intracranial pressure in patients with confirmed shunt blockage.
We reviewed 104 consecutive cases of closed dysraphism in patients seen at one institution between December 1984 and June 1987. All patients had myelographic studies, and 43 had associated CT examinations. Clinical and surgical findings (64 patients) were correlated with myelographic information. Twenty-three patients (22%) with clinical or plain film findings compatible with dysraphism had normal-appearing cords on conventional myelography, movement between supine and prone positions, and no lesions in the spinal canal. Cerebellar tonsillar ectopia (majority of tonsils between foramen magnum and C1) was found in 17 patients (16%). Six patients (6%) exhibited varying degrees of hydromyelia. In the supine position, CT-myelography of meningoceles, meningomyeloceles, or lipomeningomyeloceles may limit demonstration of the neural placode and nerve roots because of compression of the CSF-containing sac. In the decubitus position, CT scans improved demonstration of neural tissue-CSF space relationships. CT scans were useful in demonstrating anomalous paraspinal bones, diastematomyelia spurs, and spinal and sacral bone deficiency. Axial CT-myelography of intradural lipomas showed apparent neural tissue extension into the lipomas.
Seventeen patients with intracranial neoplasms that were symptomatic within the first 2 months of life were studied. Macrocrania was the commonest clinical feature, and radiologic studies including computed tomographic examination in five of the patients, showed that the tumors tended to be large, rapidly growing, and located along the neural axis. The outlook was poor, with a high operative and case mortality. The risks of irradiating young infants are discussed, and a conservative surgical approach with careful case selection is advocated.
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Neurological deterioration sometimes follows removal of cerebro-spinal fluid by lumbar puncture below a spinal block caused by a tumour. Experience has shown that similar impaction of a spinal intradural tumour may occur following the draining of hydrocephalus. We have used the term "upward spinal coning " to describe this and report four cases in which impaction of an intradural metastasis occurred when the obstructive hydrocephalus caused by the primary intracranial tumour was relieved. The possible mechanisms are discussed. Awareness of the syndrome is important for early diagnosis and treatment and motor power should be assessed regularly following the relief of hydrocephalus caused by a tumour known to seed in the spinal subarachnoid space.
One hundred infants with intracranial tumors symptomatic during the 1st year of life were studied. They differed from older children in having a higher percentage of supratentorial tumors and in the fact that 90% of the tumors were of neuroectodermal origin. Vomiting, alteration of psychomotor development, and macrocrania were the most common presenting features. The "diencephalic syndrome" was seen in 5 infants, and subarachnoid hemorrhage due to tumor was diagnosed in 4. Computed tomography as the primary investigation is increasing the number of neoplasms diagnosed in this age group, although review of the skull roentgenograms in the series disclosed an abnormality in 92%. Eighty of the tumors were verified, 68 by a cranial operation and the rest at autopsy. Of the verified neoplasms, 20% were medulloblastomas, 12.5% were choroid plexus papillomas, and 10% were cerebellar astrocytomas. The cumulative average survival was 27 months but, for those who underwent a tumor operation, the average survival was 37 months. The operative mortality was 30%. Thirty-nine patients were irradiated, and this subset had a 5-year survival rate of 43%. The morbidity was high irrespective of radiotherapy; 60% of those who survived 1 year were moderately or severely disabled. Those infants receiving more than 5000 rads of whole brain radiation tended to have greater deficits in the long term. When analyzed separately, patients treated after 1970 had greatly improved mortality and morbidity rates.
A retrospective and prospective study was made of 82 attacks of acute pancreatitis occurring in 80 patients. Attacks were defined as mild (55) or severe (27) according to clinical criteria. Severe attacks were associated with significantly low levels of uncorrected calcium and calculated ionized calcium, both at the time of admission and 48 h later. Patients with severe attacks were found to have lower levels of parathyroid hormone than either those with mild attacks or other patients who had undergone an abdominal operation. These results indicate that severe pancreatitis is associated with true hypocalcaemia, and that deficiency of circulating parathyroid hormone may be a factor in its production.
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A detailed clinical and radiological study of 51 patients presenting with a subarachnoid haemorrhage, for which no cause could be found, has been described. Although selection for full investigation has favoured the inclusion of younger and fitter patients, analysis of the information obtained suggests that haemorrhage could be due to: (a) aneurysms undergoing thrombosis at the time of haemorrhage, in which subsequent recanalisation will produce a low incidence of further bleeding; (b) minute (2 mm) aneurysms, destroyed at the time of haemorrhage and posing no subsequent threat.
The diagnostic accuracy of computerised transverse axial tomography in predicting the pathology underlying cases of nontraumatic intracerebral haematoma has been reviewed. A 160 X 160 matrix was used and the scans of one hundred patients whose diagnoses had been confirmed by either angiographic or post-mortem examination were studied. In the absence of any clinical information a diagnosis of either cerebral aneurysm or primary intracerebral haemorrhage could be made with an accuracy of 90%. The haematomas most likely to be misinterpreted are those associated with angiomas and tumours, and these two lesions were responsible for six out of the ten incorrect diagnoses. In predicting the site of a ruptured aneurysm accuracy ranged from 100% for those involving the anterior cerebral artery complex to 66% for those few haematomas associated with aneurysms of the internal carotid/proximal middle cerebral artery aneurysm complex.