Biomedical subjects
Publications and source records attributed to P Steinbok.
In order to restore spinal integrity following posterior exposures of the spinal canal in children, we describe modifications of Raimondi's laminotomy technique. The use of a pneumatic dissecting tool with foot-plate to create a hinged osteoplastic laminotomy is described, as are techniques for securing the laminotomy flap in place at the end of the procedure.
The long-term functional outcome of 101 children born with meningomyelocele between 1971 and 1981 was assessed, by a combination of retrospective chart review and follow-up assessments. The children had been managed at birth using a process of nonstandardized selection. Eighty-three of the 101 patients survived after a minimum follow-up of 8.6 years, for a mortality rate of 18%. Forty-four of 83 children (53%) were community ambulators, and this correlated well with the presence of intact quadriceps function. Forty-eight children (58%) attended normal school and were grade-appropriate. Sixty-two of 83 patients (75%) were socially continent of urine, and 71/83 (86%) were socially continent of stool. Hydrocephalus was present in 93 of the 101 children in the study, and 85 children were shunted. Half of the shunted children required a shunt revision in the first year of life, and thereafter the rate of revision decreased, so that after 2 years the risk of revision was approximately 10% per year.
Selective functional posterior rhizotomy (SFPR) is a popular operation for the treatment of spasticity in children with cerebral palsy, but the physiologic basis of the procedure is poorly understood. As part of SFPR operations in 60 consecutive children, the responses to electrical stimulation of posterior lumbosacral roots and rootlets, and the corresponding anterior roots were studied. In addition, similar electrical stimulation of posterior roots was performed in four nonspastic "control" children. Sustained responses to 50 Hz stimulation, one of the criteria used to signify abnormality in the spastic children, was found frequently in the "control" children. Contralateral spread to the lower limb muscles and suprasegmental spread to the upper limbs, face, and neck were determined to be the most valid criteria which differentiated abnormal from normal responses. Stimulation of anterior nerve roots at 50 Hz caused sustained responses and ipsilateral lower limb spread, at a low threshold compared to that of corresponding posterior roots. The results of this study bring into question the validity of some of the criteria that are used to select abnormal posterior rootlets in the SFPR procedure, and suggest criteria that may be more valid based on findings in nonspastic children.
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This study reports the use of intrathecal baclofen in two ventilator-dependent children with severe spasms secondary to spinal-cord injury. Baclofen was delivered via a subcutaneously implanted, programmable pump. The children were followed for 12 and 24 months. Baclofen dramatically reduced spasms, resulting in more stable ventilation, improved ease of care, reduced distress and better integration into the community. Although effective, intrathecal baclofen represents a significant intervention; careful consideration must be given to potential complications and the need for long-term management. Full effectiveness was dependent on free CSF flow.
Fifty consecutive children are described with spastic cerebral palsy treated with selective functional lumbar and sacral rhizotomy and followed for a minimum of 6 months. In all patients, spasticity improved postoperatively, but this was not necessarily accompanied by a functional improvement. Eighteen children who could not walk preoperatively were able to do so after rhizotomy. All 17 children who could walk preoperatively could do so following surgery, and in 15, gait was improved. Complications included transient urinary dysfunction in 4 children and sensory loss in 1. The operative procedure evolved with time: the technique of replacement laminotomy was refined; the electrophysiologic basis for selection of nerve rootlets changed after studies of nonspastic controls; smaller percentages of the L3 and L4 roots were sectioned in an attempt to prevent postoperative weakness of quadriceps, and there was a trend in the most recent patients to cut a smaller portion of all the posterior roots.
The technique for freeing adherent ventricular catheters is described in which a Bugbee wire, insulated except for the tip, is used to deliver a monopolar coagulating current to the tissue adherent to the drainage holes of the catheter. This may have some advantage over the use of an uninsulated metal cannula for delivery of a unipolar diathermy cutting current. The technique described has permitted effective and safe removal of adherent ventricular catheters.
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Intramedullary spinal cord tumors are uncommon in children, and delayed diagnosis is common. Unlike the situation in adults, low-grade astrocytomas predominate followed by ependymomas and other gliomas. Recent technological advances, including MR imaging, intraoperative ultrasonography, the ultrasonic surgical aspirator, and the operative laser, have made radical resection of intramedullary tumors feasible. The long-term results of modern-day surgery using these techniques are only now becoming available, and the role of adjuvant radiotherapy or chemotherapy for the usual low-grade tumors remains unclear. The risk of spinal deformity after laminectomy in children and the effects of radiotherapy on the growing spine create special challenges in the treatment of pediatric intramedullary tumors.
Enhanced and non-enhanced computed tomography (CT) brain scans were performed within 72 h of surgery on 21 children in whom brain tumors had been resected totally or subtotally, and scans were repeated at varying intervals thereafter. Biopsies of the resection margins were performed in 12 patients at the end of the surgical procedure. The immediate CT scan showed enhancement in the resection margin in 13 of the 21 patients and in 9 of the 13, the enhancement disappeared on follow-up scans. There was discordance between the results of immediate CT scan examination and the biopsies of the resection margins in 7 of the 12 cases. The advantages and disadvantages of an immediate postoperative scan versus a more delayed CT scan are discussed.
Two hundred and eight patients with meningomyeloceles were reviewed to assess the role of birth trauma in the pathogenesis of their neurological deficit. Vaginal breech-delivered patients appeared to have poorer neurological function in the newborn period. The factors responsible include: (1) a mid or upper lumbar level, that by sparing hip flexors and knee extensors, predisposes to breech presentation; (2) limb posturing due to residual neurological function and intrauterine positioning that limits the accurate neurological assessment of the newborn; (3) nervous system or soft tissue injury due to labor and delivery. Regardless of the mechanism, vaginal breech-delivered patients showed improvement in function, and eventually exhibited ambulatory function comparable to those infants born by cesarian section or vaginally after vertex presentation and labor. In our patient population, elective cesarian section did not offer a spinal cord or ambulatory advantage over vaginal delivery for those pregnancies presenting in a vertex fashion. Thus, it should be reserved for fetuses who are presenting breech or who have other obstetrical indications for operative delivery.
Between 4% and 8% of cases of spina bifida cystica occur in a cervical or cervicothoracic location. Despite a large body of literature concerning spinal dysraphism, there has been little written specifically about patients afflicted with this disorder in a cervical location. Eight children who presented at birth with posterior cervical or cervicothoracic lumps, all of which represented a dysraphic state, are discussed. Two types of abnormalities were noted. Three patients had hydromyelia with an associated myelocystocele herniating posteriorly into a meningocele sac. In these three patients there was an associated Chiari II malformation and hydrocephalus. The other five children had a meningocele in which a band of tissue extended from the posterior aspect of the spinal cord through a defect in the bone and fascia to the posterior part of the meningocele sac itself. No patient had a lesion that could be described as a meningomyelocele. The investigation and surgical management of these conditions are discussed and the need for intradural exploration to untether the spinal cord in the cervical region is stressed.
Six children (ages 2 to 14 years) with recurrent or poor risk primary brain tumors were treated with the '8 drugs in 1 day' chemotherapy regimen. As renal function deteriorated (median after five cycles), carboplatin was substituted in place of cisplatin at a median dose of 300 mg/m2 as a one hour infusion at hour three. Four patients also had their lomustine deleted and replaced by etoposide 100 mg/m2 at hour four. Compared to earlier cycles of chemotherapy, there was a moderate increase in transfusion requirement (especially platelets) but the incidences of fever and neutropenia were unchanged. Glomerular function as measured by nuclear glomerular filtration rate (GFR) remained unchanged or improved at the end of therapy. The severity of nausea and vomiting after substitution was markedly improved. Four of the six patients are still in complete remission 19 to 41 months after diagnosis or recurrence. It is feasible to substitute carboplatin and etoposide into the '8 drugs in 1 day' regimen when extramedullary toxicity is found.
Spinal deformity is not usually regarded as a potential complication of posterior fossa tumor resection. After cervical subluxation had been recognized in 2 children following removal of posterior fossa tumors, a review was carried out to determine the incidence of this complication. Of the 72 children who had undergone resection of a posterior fossa tumor, 4 patients, including the original 2, developed a cervical spinal deformity. Factors that predisposed to this complication included laminectomy of C2 or lower, local wound complications and possibly post-operative neck weakness. It is important to be aware that cervical subluxation can occur after resection of posterior fossa tumors, when laminectomy extending below C1 has been performed. Patients at risk should be followed closely.
A modification of the technique combining sagittal strip, circular occipital and biparietal wedge craniectomies (Albright's procedure) for the treatment of sagittal synostosis, with prominent occipital bossing, is described. "Keyhole," as opposed to wedge, parietal craniectomies allow improvement in the shape of the skull, beginning intraoperatively, while eliminating the outbending of the parietal bone that occurs at the apex of a wedge craniectomy.
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The significance and cause of ventriculomegaly in achondroplasia was investigated in five achondroplastic children. The intraventricular pressure (IVP) was monitored over 24 hours, followed by intraventricular injection of radionuclide alone or in combination with water-soluble contrast material. The IVP was elevated and the reabsorption of cerebrospinal fluid (CSF) into the sagittal sinus was slow in all cases, but there was no obstruction to CSF flow. The spinal subarachnoid space was well seen in all patients. Jugular venograms with pressure monitoring were obtained in four patients (bilaterally in one). These studies confirmed a narrow jugular foramen in all patients with a significant venous pressure gradient (3 to 10 mm Hg) obtained while the catheter was being pulled back from the sigmoid sinus through the foramen. A second gradient was found in the jugular vein in two patients at the level of the upper thoracic aperture. This gradient was 6 and 14 mm Hg, respectively. Identical venograms and monitoring of the venous pressure in a control group showed no pressure gradients across the jugular foramen and smaller gradients (2 to 5 mm Hg) across the thoracic inlet. It is concluded from these studies that ventriculomegaly in achondroplastic children represents hydrocephalus, which is likely secondary to raised intracranial venous pressure due to hemodynamically significant stenosis of the jugular foramen and, in some cases, the jugular vein in the thoracic aperture.
A case is reported of methotrexate leukoencephalopathy presenting as an intracerebral rim-enhancing mass lesion of CT scan. The implications of this rare presentation of methotrexate leukoencephalopathy for therapy are discussed.