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Matthew D Smyth

Publications and source records attributed to Matthew D Smyth.

At least 19 recordsLinked to original sources
PubMed2006

Simultaneous image-guided and endoscopic navigation without rigid cranial fixation: application in infants: technical case report.

OBJECTIVE AND IMPORTANCE: Infants and young children demonstrate a variety of intraventricular and periventricular lesions. Endoscopy has proven useful in the treatment of many of these lesions, but its benefit is limited if it is applied to complex loculated cysts or if the disease is concealed by normal ependymal boundaries. In adults and older children, endoscopy can be augmented by the simultaneous use of frameless stereotaxy, but this combined modality has not been possible in infants and young children without rigid cranial fixation. We describe a method of achieving simultaneous stereotactic and endoscopic navigation in infants and young children by using a pinless, frameless stereotactic assembly. CLINICAL PRESENTATION: The first patient was a 6-week-old boy with macrocephaly and a bulging fontanelle. Computed tomographic and magnetic resonance imaging revealed a complex arachnoid cyst and obstructive hydrocephalus. The second patient was a 7-month-old, ex-premature (27-wk gestational age) boy who developed posthemorrhagic hydrocephalus. He underwent multiple shunt revisions, one of which was complicated by enterococcal ventriculitis. Despite bilateral ventriculoperitoneal shunts, he developed increasing head circumference, listlessness, and irritability. Imaging revealed an enlarged, multiloculated, and asymmetric ventricular system. INTERVENTION: Simultaneous image-guided and endoscopic neuronavigation was implemented in both patients. Before the procedure, a cranial reference arc was secured to the outer table of the cranium through a small incision adjacent to the operative field. After the stereotactic apparatus was registered, the software was used to plan a trajectory for the approach. A burr hole was then made, and a rigid 6-mm endoscope was inserted for direct visualization. Once advanced past the endoscopic port tip, the electromagnetic coil stylet was used to stereotactically track position and identify areas for fenestration, biopsy, and catheter insertion. CONCLUSION: Endoscopic views of complex hydrocephalus and arachnoid cysts alone are often difficult to interpret. Simultaneous image-guided and endoscopic neuronavigation may be advantageous in the management of complex cases that are anatomically related to the ventricular system in infants for whom rigid cranial fixation could lead to increased procedure-related morbidity.

Brain Diseases↗
PubMed2006

Pediatric neurosurgical injuries associated with all-terrain vehicle accidents: a 10-year experience at St. Louis Children's Hospital.

OBJECT: All-terrain vehicles (ATVs) have been characterized as inherently unstable and are associated with significant pediatric injuries in the US. The authors performed a study to analyze data obtained in pediatric patients who had sustained neurological injuries in ATV-related accidents, identify potential risk factors, and propose preventive measures. The study is based on a 10-year experience at the St. Louis Children's Hospital. METHODS: The authors retrospectively analyzed data obtained in all patients admitted to the St. Louis Children's Hospital between 1993 and 2003, limiting their focus to pediatric cases involving ATV-related accidents. A total of 185 patients were admitted with these criteria. Sixty-two patients (33.5%) suffered neurological injuries; there were 42 male and 20 female patients whose age ranged from 2 to 17 years. The most common injuries included skull fracture (37 cases) and closed head injury (30 cases). There were 39 cases of intracranial hemorrhage and 11 of spinal fracture. A total of 15 types of neurosurgical procedure were performed: six craniotomies for hematoma drainage, five craniotomies for elevation of depressed fractures, two procedures to allow placement of an intracranial pressure monitor, one to allow placement of an external ventricular drain, and one to allow the insertion of a ventriculoperitoneal shunt. Two patients had sustained spinal cord injury, and three procedures were performed for spinal decompression or stabilization. The duration of hospital stay ranged from 1 to 143 days (mean 6.6 days). Fifty-seven patients (30.8%) were eventually discharged from the hospital, three (1.6%) were transferred to another hospital, two (1.1%) died, and 123 (66.4%) required in-patient rehabilitation. CONCLUSIONS: Children suffered significant injuries due to ATV accidents. In passengers there was a statistically significant increased risk of neurological injury. The relative risk of neurological injury in patients not wearing helmets was higher than that in those who wore helmets, but the difference did not reach statistical significance. Further efforts must be made to improve the proper operation and safety of ATVs, both through the education of parents and children and through the creation of legislation requiring stricter laws concerning ATV use.

Adolescent↗
PubMed2005

Focal cooling for epilepsy: an alternative therapy that might actually work.

The therapy of focal epilepsy remains inadequate. Many patients who have localization-related seizures find themselves either overmedicated with anticonvulsants or suffering from frequent seizures. While surgical resection can lead to excellent outcomes in up to 60% of patients with neocortical epilepsy, there are obviously many who either fail surgery or are deemed inappropriate surgical candidates. We are currently determining the efficacy of local cooling for the therapy of certain focal epilepsies. We have attempted to adapt new technologies borrowed from electrical and mechanical engineering to develop cooling devices that will ultimately improve the diagnosis and therapy of these focal epilepsies. The present review describes the rationale for this research and our progress to date.

Animals↗
PubMed2005

Transcortical cooling inhibits hippocampal-kindled seizures in the rat.

PURPOSE: When epileptogenic regions encroach on eloquent brain, surgery may incur unacceptable deficits. Reversible cooling may control seizures while preserving function. We describe the effects of cooling kindled seizures in awake, freely moving rats. METHODS: We kindled rats after placement of a bipolar electrode and a copper cooling coil in dorsal hippocampus. Fully kindled animals (three consecutive grade 5 seizures) were cooled to one of two target temperatures (24 degrees or 27 degrees C) for 3 min preceding a kindling stimulation and 2 minutes after. We compared seizure score (0-5) and afterdischarge duration (ADD) with and without cooling. Target temperatures were confirmed in identical animals by using a needle thermocouple advanced to the kindling target while circulating coolant. RESULTS: Circulation of 16 degrees C and 8 degrees C coolant reliably achieved transcortical cooling of the hippocampal target to 27.0 +/- 1.2 degrees C and 23.8 +/- 2.0 degrees C, respectively, by 180 s. Cooling with 16 degrees C coolant (n = 5) significantly reduced seizure scores from 5 to 2.57 +/- 1.56, and ADD from 142 +/- 94.5 s to 45.7 +/- 20.5 s. Cooling with 8 degrees C coolant (n = 5) reduced seizure scores from 5 to 2.0 +/- 0.42, and ADD from 132.3 +/- 29.6 s to 55.5 +/- 25.9 s. In 33.3% of all cooled stimulations, grade 0 seizures resulted; grade 5 seizures recurred during subsequent stimulations when cooling was withheld. CONCLUSIONS: Fully kindled, tonic-clonic seizures can be suppressed or aborted with periictal cooling of the kindling target. Anticonvulsant activity occurred at temperatures well above those known to result in tissue injury or inhibition of normal neurologic function. These findings have important implications for the potential use of implantable cooling devices in humans with refractory epilepsies in or near eloquent cortex or dominant hippocampal formations.

Animals↗
PubMed2005

Use of rapid-sequence magnetic resonance imaging for evaluation of hydrocephalus in children.

OBJECT: The authors examine the use of rapid-sequence magnetic resonance (rsMR) imaging to make the diagnosis of malfunctioning and/or infected shunts in patients with hydrocephalus. Computerized tomography (CT) scanning is usually used in this context because it rapidly acquires high-quality images, yet it exposes pediatric patients to particularly high levels of radiation. Standard MR imaging requires longer image acquisition time, is associated with movement artifact, and, in children, usually requires sedation. Standard MR imaging provides greater structural resolution, yet visualization of ventricular catheters is relatively poor. METHODS: The authors analyzed a series of 67 rsMR imaging examinations performed without sedation in pediatric patients with hydrocephalus whose mean age was 4 years at the time of the examination. The mean study duration was 22 minutes. Catheter visualization was good or excellent in more than 75% of studies reviewed, and image quality was good or excellent in more than 60% of studies reviewed. The authors analyzed cancer risk with a model used for atomic bomb survivors. Fifty percent of their patients with hydrocephalus had undergone more than four brain imaging studies (CT or MR imaging) in their lifetimes. For the many patients who had undergone more than 15 studies, the total estimated lifetime attributable cancer mortality risk was calculated to be at least 0.35%. CONCLUSIONS: Rapid-sequence MR imaging yields reliable visualization of the ventricular catheter and offers superior anatomical detail while limiting radiation exposure. The authors' protocol is rapid and each image is acquired separately; therefore, motion artifact is reduced and the need for sedation is eliminated. They recommend the use of rsMR imaging for nonemergent evaluation of pediatric hydrocephalus.

Adolescent↗
PubMed2005

Early programmable valve malfunctions in pediatric hydrocephalus.

OBJECT: The use of adjustable differential pressure valves has been recommended to improve ventriculoperitoneal (VP) shunt performance in selected patients; however, published data are scarce regarding their clinical reliability. Recently, the identification of a number of malfunctioning programmable valves during shunt revision surgery in children prompted a retrospective review of valve performance in this patient cohort. METHODS: The authors performed a retrospective chart analysis of 100 patients with programmable valve shunts and 89 patients with nonprogrammable valve shunts implanted at the St. Louis Children's Hospital between April 2002 and June 2004. They noted the cause of hydrocephalus, the type of shunt malfunction, and cerebrospinal fluid (CSF) protein levels. Regular clinical follow up ranged from 1 to 26 months, with a mean follow-up time of 9.75 months for patients with programmable valves and 10.4 months for patients with nonprogrammable valves. Patient ages ranged from 2 weeks to 18 years. One hundred patients had 117 programmable valves implanted, and 35 of these patients (35%) underwent shunt revision because of malfunction. The programmable valve itself malfunctioned in nine patients who had undergone shunt revision (11.1%/year of follow up). The nonprogrammable valve group had no valve malfunctions. The overall VP shunt revision rate in the nonprogrammable valve group was 20.2%. No significant differences were identified when CSF protein levels and specific malfunction types were compared within the programmable valve and nonprogrammable valve groups. CONCLUSIONS: In this study the authors demonstrated an annualized intrinsic programmable valve malfunction rate of 11.1%, whereas during the same period no intrinsic valve malfunctions were noted with nonprogrammable valve systems for similar causes of hydrocephalus. The CSF protein levels did not correlate with observed valve malfunction rates. Further evaluation in a prospective, randomized fashion will elucidate specific indications for programmable valve systems and better determine the reliability of these valves in the pediatric population.

Adolescent↗
PubMed2004

Complications of ventriculosubgaleal shunts in infants and children.

INTRODUCTION: The ventriculosubgaleal shunt has been used for the temporary bypass of the normal cerebrospinal fluid (CSF) pathways. To date, a large series of complications from this procedure has not been elaborated upon in the literature. PATIENTS AND METHODS: We retrospectively reviewed all such shunts (170) placed at our institution over the last 6 years and documented all complications from this procedure. The majority of patients operated upon were premature infants with intraventricular hemorrhage and subsequent hydrocephalus. This technique was used in a much smaller group of patients in whom the peritoneal cavities were not currently candidates for distal shunt implantation but would have been with time. Other patients in whom this technique was used were those with malignant brain tumors, intraventricular abscesses, chronic truncal wounds, chronic subdural hygromas, and meningitis. RESULTS: Complications from subgaleal shunting included infection (5.9%), intracranial hemorrhage (1.1%), and wound leakage (4.7%). CONCLUSIONS: We believe the benefits afforded by ventriculosubgaleal shunting significantly outweigh the risks of the procedure and greatly ease the burden of care for this select population of children. Based on the literature and our own experience, the complications from this procedure are not excessive or extraordinarily unique compared with other neurosurgical CSF diversion techniques.

Child, Preschool↗
PubMed2004

Eyebrow incision with supraorbital trephination for endoscopic corpus callosotomy: a feasibility study.

OBJECTIVE: We describe a novel technique for the partial bisection of the corpus callosum in order to increase the minimally invasiveness of this procedure. METHODS: Brow incisions with midline trephinations were performed in six adult cadavers. An endoscope was next introduced and used to transect approximately the anterior two-thirds of the corpus callosum. RESULTS: No complications such as injury to the superior sagittal sinus or anterior cerebral artery were encountered in any of our cadaveric specimens. The corpus callosum was easily transected in each specimen. CONCLUSION: As a feasibility study, we believe this technique could provide a less invasive mechanism for patients who require corpus callosotomy and will minimize much of the morbidity associated with the traditional methods of sectioning the corpus callosum.

Aged↗
PubMed2004

Sports and pediatric cerebrospinal fluid shunts: who can play?

OBJECTIVE: The purpose of this study was to collect and review available data on the incidence of sport-related complications in children with cerebrospinal fluid (CSF) shunts. METHODS: After review of medical and legal literature revealed no reports on sports and shunts, an Internet-based survey was conducted of pediatric neurosurgeons. Observed complications, recommendations for sport participation, and shunt volume data were collected. RESULTS: Ninety-two providers (55% sample) responded. Seventy-seven percent had never observed a sport-related shunt complication in their practice. The remaining 23% witnessed an estimated total of 25 to 30 complications. Broken shunt catheters and shunt dysfunction were the most common complications observed. Only one acute intracranial hematoma was reported in the entire series. The incidence of sport-related CSF complications in children seems to be significantly less than 1%. Ninety percent of pediatric neurosurgeons do not restrict their patients' participation in noncontact sports. For contact sports, approximately one-third of neurosurgeons preclude all participation, whereas another third restrict specific sports. The final third of neurosurgeons surveyed do not restrict participation in contact sports for children with CSF shunts. CONCLUSION: Sport-related complications in children with CSF shunts are very uncommon.

Athletic Injuries↗
PubMed2004

Intramedullary hemorrhage in a neonate after lumbar puncture resulting in paraplegia: a case report.

We present the case of a premature infant with decreased spontaneous movement of the lower extremities. Imaging was demonstrative of a lesion of the conus medullaris. Operatively and with histologic confirmation, the mass was determined to be a blood clot originating from the conus. Retrospectively, the patient had a known lumbar puncture. There were no clotting abnormalities in this patient. At long-term follow-up, the child continues to have lower extremity paresis and incontinence of bowel and bladder. Clinicians should consider the lower termination of the conus medullaris in the infant, especially in the preterm infant.

Hematoma↗
PubMed2004

Efficacy of scheduled nonnarcotic analgesic medications in children after suboccipital craniectomy.

OBJECT: The authors performed a study to evaluate the efficacy of a regimen of scheduled minor analgesic medications in managing postoperative pain in children undergoing intracranial procedures. METHODS: Postoperative pain scores were analyzed in two groups of children who underwent decompressive surgery for Chiari malformation: Group A underwent a scheduled regimen of minor oral analgesic medications (standing doses of acetaminophen [10 mg/kg] and ibuprofen [10 mg/kg] alternating every 2 hours) and Group B received analgesic medication when requested. Fifty children underwent a standard occipital craniectomy (25 in each group). The pain scores were significantly lower in Group A during most of the postoperative period. Length of stay (LOS) was shorter (2.2 compared with 2.8 days), and narcotic and antiemetic requirements were also lower in Group A patients than in Group B patients. Patients with spinal cord syringes exhibited a similar postoperative status to those without, and similar improvements in pain scores with scheduled minor analgesic medications were also evident. CONCLUSIONS: A regimen of minor analgesic therapy, given in alternating doses every 2 hours immediately after craniotomy and throughout hospitalization, significantly reduced postoperative pain scores and LOS in children in whom suboccipital craniotomy was performed. Narcotic and antiemetic requirements were also decreased in association with this regimen. Application of this postoperative analgesia protocol may benefit children and adults in whom various similar neurosurgical procedures are required.

Acetaminophen↗
PubMed2004

Arachnoid veils and the Chiari I malformation.

OBJECT: The literature contains scant data regarding variations in anatomy at the level of the foramen of Magendie in patients with Chiari I malformation and syringomyelia. METHODS: Based on their operative experience and hospital data, the authors detailed the incidence of arachnoid veils found in juxtaposition to the foramen of Magendie in patients with hindbrain herniation. Additionally, radiological studies were retrospectively reviewed in cases in which such an anomaly was noted intraoperatively. Of 140 patients with Chiari I malformation who underwent decompressive surgery, an associated syrinx was demonstrated in 80 (57%). The foramen of Magendie was obstructed by an arachnoid veil in 10 (12.5%) of these patients; once the lesion was punctured, the cerebrospinal fluid drained freely from this median aperture. On retrospective review of imaging studies, none of these anomalous structures was evident. In all patients with an arachnoid veil and syringomyelia resolution of syringomyelia was revealed on postoperative imaging. CONCLUSIONS: In the absence of a clear pathophysiology of syrinx production, the authors would recommend that patients with syringomyelia and Chiari I malformation undergo duraplasty so that, if present, these veils can be fenestrated.

Adolescent↗
PubMed2004

Magnetic resonance imaging evidence of posterior pharynx denervation in pediatric patients with Chiari I malformation and absent gag reflex.

OBJECT: The authors hypothesized that children with preoperative Chiari I malformation and an absent gag reflex may harbor pharyngeal musculature atrophy identifiable on magnetic resonance (MR) imaging. METHODS: Thirty patients with preoperative Chiari I malformation and a functioning gag reflex, five patients with preoperative Chiari I malformation and complete absence of gag reflex, and 50 control individuals underwent radiological measurement of the posterior pharyngeal wall thickness. The thickness of the posterior pharyngeal wall in age-matched controls was significantly thinner (p < 0.0001) than that in patients with Chiari I malformation and no functioning gag reflex. Additionally, in patients with hindbrain herniation and absent gag reflex, the posterior pharyngeal wall thicknesses were comparable to or thinner than those in age-matched controls. A general decrease in the thickness of the posterior pharyngeal wall was found in control individuals who were older compared with patients with Chiari I malformation and a preserved gag reflex in whom the prevertebral soft tissues were found to increase in thickness with age. Analysis of these data showed that in children with a nonfunctioning gag reflex the prevertebral soft tissue, composed primarily of the superior constrictor muscle, is statistically thinner compared with that in age-matched controls and age-matched children with Chiari I malformation and a functioning gag reflex. The authors theorize that the discrepancy between this measurement in controls and patients with hindbrain herniation is due to the thickening of the craniocervical ligaments that is known to occur in this clinical entity. CONCLUSIONS: The finding that prevertebral soft tissue thickens with age in patients with Chiari I malformation and functioning gag reflex alone may aid in the interpretation of soft-tissue injury following cervical spine injuries in this group.

Adolescent↗
PubMed2003

Cutaneous manifestations and the Chiari I malformation.

This article presents a child with Chiari I malformation and cutis marmorata telangiectatica congenita and reviews the medical literature regarding Chiari I malformation and other cutaneous disorders. In addition to cutis marmorata telangiectatica congenita and Chiari I malformation, our patient exhibited hemihypertrophy, Tourette's syndrome, scoliosis, obsessive-compulsive disorder, and seizures. Other associated findings seen in patients with Chiari I malformation include basilar invagination, Klippel-Feil syndrome, atlantoaxial assimilation, scoliosis from an underlying syrinx, and hydrocephalus.

Arnold-Chiari Malformation↗
PubMed2003

Late gestational intrauterine myelomeningocele repair does not improve lower extremity function.

OBJECTIVE: To determine whether intrauterine myelomeningocele repair performed at between 20 and 28 weeks gestation improves lower extremity function (LEF). METHODS: Thirty-seven consecutive patients who had undergone intrauterine repair of their myelomeningocele at Vanderbilt University Medical Center had their lower extremity function and radiographic level (first defective vertebral level) compared to these same parameters in 40 controls who had undergone traditional postgestational repair of their myelomeningocele at the Children's Hospital in Birmingham, Ala., USA. RESULTS: Of all 77 patients (controls and study group), 13 had a LEF that matched their radiographic level, 27 had a LEF that was rostral to their radiographic level, and 37 had a LEF that was caudal to their radiographic level. Further stratification revealed that for the intrauterine repaired myelomeningoceles, 11% had no difference between LEF and radiographic level, 43% had a LEF that was rostral to their radiographic level, and 46% had a LEF that was caudal to their radiographic level. For those closed in a traditional manner, LEF matched their radiographic level, was rostral to their radiographic level, and was caudal to their radiographic level in 22.5%, 27.5%, and 50% respectively. However, the overall mean differences between institutions produced a p-value of 0.2026 (paired t-test). CONCLUSIONS: Although the current timing of intrauterine myelomeningocele repair has been found to lessen the degree of herniation of the rhombencephalon and reduce the incidence of shunt-dependent hydrocephalus, it does not statistically improve LEF. Parents should be advised of these findings prior to surgical intervention so as to focus their expectations.

Female↗
PubMed2003

Hemihypertrophy and the Chiari I malformation.

We report two children with hemihypertrophy and Chiari I malformation (CIM) and review the extant medical literature regarding CIM and overgrowth disorders. We propose that these two entities do not represent a spurious association but rather share a common dysembryology of mesoderm.

Arnold-Chiari Malformation↗