Lipomas of the spinal cord are among the most fascinating lesions encountered by the pediatric neurosurgeon. An understanding of spinal lipomas may, however, be difficult because the terminology used to describe the accumulations of spinal fat is confusing, inconsistently applied, and at times contradictory. An anatomical characterization of lipomas may assist in understanding these lesions. Lipomas of the spinal cord are very rare and cause symptoms related to mass effect and secondary compressive myelopathy. Lipomas of the conus medullaris (or lipomyelomeningocele) are the most common form of fatty masses in the spine and can be divided into dorsal, caudal, and transitional forms. These lesions are a manifestation of occult spinal dysraphism and a common cause of the tethered cord syndrome (TCS). The natural history of untreated lipomyelomeningocele, although incompletely understood, appears to be progressive neurological deterioration with loss of bladder control. Timely, careful surgical intervention may prevent significant neurological deterioration and progressive disability in the majority of children harboring these lesions. In surgical intervention the surgeon seeks to disrupt the connection between the fibrofatty mass and underlying cord as well as to reestablish normal anatomical planes. Several intraoperative video segments illustrating lipomyelome-ningocele resection are included in this paper. Lipomas of the terminal filum (fatty filum) are truly occult and are also associated with TCS. Surgical treatment of filum lipomas carries significantly lower risk than that for lipomas of the conus medullaris. Again, the goal of surgery is to disrupt the connection between the abnormal fibrofatty tissue and the underlying spinal cord.
Jeffrey P. Blount and Scott Elton
Elizabeth N. Kuhn, Betsy Hopson, Michael J. Conklin, and Jeffrey P. Blount
Patients with myelomeningocele are often affected by scoliosis and tethered cord syndrome, and frequently require spine surgery. Intradural spine surgeries may carry an inherently higher risk of inducing shunt malfunction due to entry into the subarachnoid space. In this study, the authors sought to compare rates of shunt malfunction after intradural and extradural spine surgeries among pediatric patients with myelomeningocele.
The authors reviewed records of the National Spina Bifida Program Registry for Children’s Hospital of Alabama. The Exago reporting function was used to identify patients who had received at least one of the following procedures: shunt revision, tethered cord release (TCR), or spinal fusion for deformity. The registry records were reviewed for all identified patients to determine if a shunt revision was performed within the 1st year after TCR or spinal fusion.
Final analyses included 117 patients, of whom 39 underwent spinal fusion and 78 underwent TCR. Among patients who underwent spinal fusion, shunt revision was performed within 30 days in 2 patients (5.1%), within 60 days in 2 (5.1%), within 90 days in 4 (10.3%), and within 1 year in 5 (12.8%). Among patients who underwent TCR, shunt revision was performed within 30 days in 7 patients (9.0%), within 60 days in 10 (12.8%), within 90 days in 11 (14.1%), and within 1 year in 17 (21.8%). Using the log-rank test, there was no significant difference in Kaplan-Meier curves between intradural and extradural groups (p = 0.59).
In a review of single-institution registry data, the authors found no statistically significant difference in the risk of shunt malfunction after intradural and extradural spine surgeries.
Report of three cases
Jeffrey P. Blount, Kent B. Remley, Samuel K. Yue, and Donald L. Erickson
✓ Intrathecal morphine delivered by implanted pumps has been used in the treatment of pain caused by terminal cancer. Some authors supports its use in benign pain as well. The authors present three cases in which chronic infiltration of intraspinal narcotic medication was complicated by the formation of a granulomatous mass that became large enough to exert mass effect and induce neurological dysfunction.
Jeffrey P. Blount, Amber S. Gordon, Paul M. Foreman, and John H. Grant
The authors report on an infant with a bifrontal encephalocele that was associated with multisuture craniosynostosis, spasticity, and a progressively severe epilepsy. They describe the initial presentation, genetic screening results, staged multidisciplinary operative plans, clinical course, complications, and long-term surgical and developmental follow-up. To their knowledge, the comprehensive surgical management of this type of complicated congenital cranial anomaly has not been previously described.
Surgical management was staged and multidisciplinary and required careful attention to all 3 components of the condition: 1) hydrocephalus, 2) frontal meningoencephalocele, and 3) epilepsy.
Jeffrey P. Blount, R. Shane Tubbs, W. Jerry Oakes, and Robin P. Humphreys
✓ Arteriovenous malformations (AVMs) are the most common cause of intracerebral hemorrhage in children. In this paper the authors trace the historical evolution of the recognition, diagnosis, and treatment of pediatric intracerebral AVMs, and they summarize the contemporary approach and current controversies surrounding treatment of these lesions. Important distinctions between adult and pediatric AVMs are emphasized.
Jeffrey P. Blount, W. Jerry Oakes, R. Shane Tubbs, and Robin P. Humphreys
✓ Vein of Galen aneurysmal malformations are a mixed group of lesions characterized by an abnormal fistula between abnormal distal branches of the choroidal and/or posterior cerebral arteries and the great vein of Galen. In this paper the authors trace the historical evolution of the current approach to diagnosis and treatment, and the literature is reviewed comprehensively. During the historical era, vein of Galen malformations were described in individual case reports and an early classification system was developed. In the early era of treatment, open surgery was the preferred approach, although morbidity and mortality rates were high. The development of neurointerventional techniques allowed the introduction of occlusive materials into the fistula, with pronounced improvements in clinical outcome.
Jeffrey P. Blount, W. Jerry Oakes, R. Shane Tubbs, and Robin P. Humphreys
✓ Intracranial aneurysms are rare in children, and their origins and treatment methods tend to be different from those in these same entities in adults. These lesions tend to be congenital or to have an infectious or traumatic origin. In the current paper the authors trace the historical evolution of the diagnosis and treatment of intracranial aneurysms in children. Based on the literature, these lesions appear to occur in children in less than 3% of all series. The literature also supports the suggestion that symptoms from these aneurysms are often from mass effect and that giant aneurysms and lesions in the posterior cranial fossa are relatively more common in children than in adults. The termination of the carotid artery and the anterior cerebral artery seem to be disproportionately common sites of aneurysm formation in this cohort. Interestingly, surgical outcomes in children appear to be moderately better than in adults. Based on the literature, the claim can be made that a multidisciplinary approach to the management of such aneurysms can yield good outcomes in a very high percentage of children treated.
R. Shane Tubbs, John C. Wellons III, Jeffrey P. Blount, and W. Jerry Oakes
✓ The authors describe the use of autogenetic posterior atlantooccipital (PAO) membrane for duraplasty following after posterior cranial fossa surgery. The PAO membrane is routinely exposed for procedures of the posterior cranial fossa and merely needs to be dissected free of the underlying dura mater. Recently this membrane was obtained in several pediatric patients following procedures of the posterior cranial fossa such as duraplasty in case of Chiari I malformation. No postoperative complications were found at 6-month follow-up examination. The advantages of this intervention include less manipulation of muscle and fascia than that involved in other procedures and, therefore, seemingly less postoperative pain and the negation of issues inherent with foreign-body graft sources. The authors believe this structure to be of use as a dural substitute in small dural openings of the posterior cranial fossa.
Hyunmi Kim, Catherine Lee, Robert Knowlton, Curtis Rozzelle, and Jeffrey P. Blount
Depth electrodes provide a better sampling of sulci and regions of cortex that lie tangential to the plane of subdural electrodes. The aim of this study was to evaluate the utility of supplemental depth electrodes in the surgical treatment of pediatric patients with neocortical epilepsy.
Cases involving 12 consecutive pediatric patients (mean age [SD] 10.9 ± 4.4 years) were reviewed. Focal resective surgery (in 9 cases) or functional hemispherectomy (in 3 cases) was performed after intracranial monitoring. The mean total number of electrodes was 118 ± 29; the mean numbers of grid, strip, and depth electrodes were 95 ± 27, 10 ± 6, and 13 ± 5, respectively The most common pathological condition was focal cortical dysplasia.
In 4 cases, depth electrodes demonstrated the ictal onset zone in an area not easily accessible by grids or strips (in the basal temporal region in 3 cases and the upper opercular region in 1 case). In 3 of these 4 cases, the ictal onset zone was defined exclusively by the depth electrodes. In each of these 3 cases, the surface electrodes (on grids or strips) demonstrated early propagation but not ictal onset. In 9 cases, the depth electrodes also demonstrated the early propagation zone. The information about the ictal onset zone and the early propagation zone helped to provide additional information that affected the extent (in 7 cases) or depth (in 3 cases) of the resection. The proportion of the electrodes involved in resection relative to the total number of implanted electrodes was low (mean ± SD, 0.26 ± 0.09). Nine patients (75.0%) became seizure free (Engel class IA outcome) after surgery (mean duration of follow-up 25.7 ± 4.29 months). There were no surgical complications related to intracranial electroencephalography monitoring.
Most patients (75.0%) became seizure free after extensive monitoring and more limited resection of seizure-onset regions. Supplemental depth electrodes contribute to improved outcome by providing information about the ictal onset zone that is not accessible by grid or strip electrodes in some cases. The supplemental depth electrodes conferred an extra dimension of depth to the analysis, which allowed for successful outcome with more limited resection.
Matthew D. Smyth, R. Shane Tubbs, E. Martina Bebin, Paul A. Grabb, and Jeffrey P. Blount
Object. The aim of this study was to define better the incidence of surgical complications and untoward side effects of chronic vagus nerve stimulation (VNS) in a population of children with medically refractory epilepsy.
Methods. The authors retrospectively reviewed the cases of 74 consecutive patients (41 male and 33 female) 18 years of age or younger (mean age 8.8 years, range 11 months–18 years) who had undergone implantation of a vagal stimulator between 1998 and 2001 with a minimum follow up of 1 year (mean 2.2 years). Of the 74 patients treated, seven (9.4%) had a complication ultimately resulting in removal of the stimulator. The rate of deep infections necessitating device removal was 3.5% (three of 74 patients who had undergone 85 implantation and/or revision procedures). An additional three superficial infections occurred in patients in whom the stimulators were not removed: one was treated with superficial operative debridement and antibiotic agents and the other two with oral antibiotics only. Another four stimulators (5.4%) were removed because of the absence of clinical benefit and device intolerance. Two devices were revised because of lead fracture (2.7%). Among the cohort, 11 battery changes have been performed thus far, although none less than 33 months after initial implantation. Several patients experienced stimulation-induced symptoms (hoarseness, cough, drooling, outbursts of laughter, shoulder abduction, dysphagia, or urinary retention) that did not require device removal. Ipsilateral vocal cord paralysis was identified in one patient. One patient died of aspiration pneumonia more than 30 days after device implantation.
Conclusions. Vagus nerve stimulation remains a viable option for improving seizure control in difficult to treat pediatric patients with epilepsy. Surgical complications such as hardware failure (2.7%) or deep infection (3.5%) occurred, resulting in device removal or revision. Occasional stimulation-induced symptoms such as hoarseness, dysphagia, or torticollis may be expected (5.4%).