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Biomedical subjects

Michael L Levy

Publications and source records attributed to Michael L Levy.

35 records · Page 2Linked to original sources
PubMed2004

Bacterial adhesion to surfactant-modified silicone surfaces.

OBJECTIVE: Ventricular shunt infections are a major contributor to morbidity in patients being treated for hydrocephalus. The majority of these infections are from Staphylococcus epidermidis. Prevention of bacterial adhesion to the silicone surface of a ventricular catheter could decrease shunt infections. We studied the effectiveness of a surfactant and/or 2% iodine prewash on preventing bacterial adhesion to Silastic catheter material. METHODS: In a laboratory setting, various concentrations of a surfactant, Poloxamer-188 (P188), and a bactericidal agent, iodine, were compared against a control solution in their ability to prevent bacterial adhesion of S. epidermidis to a silicone surface. Silicone wafers were soaked for 1 hour in the test solution, then inoculated and incubated with S. epidermidis for 24 hours. Bacterial counts were then obtained and compared. RESULTS: The most effective method tested in this study was 20% P188, which allowed only 3.02% bacterial adhesion compared with 22.2% bacterial adhesion in the control (P < 0.001). P188 at a 10% concentration or 20% mixed with iodine had the next most effective inhibition. Of the germicidal solutions, a 5-ppm solution of iodine was the most effective. The most ineffective method tested was 2 ppm iodine, which allowed 13.2% bacterial adhesion. CONCLUSION: Use of a surfactant and/or a germicidal will provide some protection against bacteria attaching to silicone surfaces before they are surgically implanted. The use of a surfactant soak of 20% P188 or iodine at a concentration of 5 ppm before inoculation with S. epidermidis significantly decreased the bacterial adhesion to silicone wafers. This finding has relevance to clinical practice because it highlights a simple step undertaken before implanting a ventricular catheter that could reduce the adhesion rate of the most common contaminant of these catheters. This step may become an important factor in decreasing infection rates in shunt-dependent patients.

Anti-Infective Agents, Local↗
PubMed2004

Vertebral body granuloma of the cervical region after pencil injury.

OBJECTIVE AND IMPORTANCE: Granuloma formation has been reported as a rare complication of pencil lead injury. Insufficient data exist regarding pencil lead injuries of the cervical spine. We present the findings in an 18-year-old male patient with secondary granuloma formation after a penetrating transoral pencil injury. We suggest that imaging characteristics and a detailed history will assist with the diagnosis of such lesions. CLINICAL PRESENTATION AND INTERVENTION: The patient was an 18-year-old man who presented with cervical pain. His history included falling as a child while having a pencil in his mouth. T2-weighted imaging studies documented a 1- x 1-cm enhancing lesion posterior to the vertebral body at the C3 level. The patient underwent a C3 vertebrectomy, and specimens were notable for infection, pencil lead, and granuloma formation. CONCLUSION: In the evaluation of a potential granuloma or mass lesion of the cervical spine in a child or adolescent, the differential diagnosis may include a neoplasm. Although computed tomography is an ideal tool to detect foreign objects, including pencil leads, only awareness of the potential for pencil lead injuries and that pencil lead fragments may remain unrecognized on computed tomographic scans will assist the physician in diagnosing such injuries.

Adolescent↗
PubMed2004

A neuroforensic analysis of the wounds of President John F. Kennedy: Part 2--A study of the available evidence, eyewitness correlations, analysis, and conclusions.

A substantial body of literature exists surrounding the assassination and subsequent pathological examination of President John F. Kennedy. In the first part of this series, we provided a previously undocumented eyewitness account by a neurosurgeon of what transpired in Trauma Room 1 of Parkland Memorial Hospital on November 22, 1963. The current article reviews the copious literature and extensive controversy regarding President Kennedy's wounds. The autopsy report, ballistics data, official reviews of the autopsy data, and Dr. Grossman's observations are correlated in an effort to provide a neuroforensic analysis of the nature of the wounds that President Kennedy sustained. The final article of the series will relate the wounds to the timing of the shots and the location of the President as his limousine traversed Dealey Plaza and will discuss the sites from which the bullets could have been fired.

Autopsy↗
PubMed2004

Leptomeningeal cyst development after endoscopic craniosynostosis repair: case report.

OBJECTIVE AND IMPORTANCE: Endoscopically assisted (minimally invasive) craniosynostosis repair has been suggested as an alternative to traditional open craniosynostosis repair. Advocates of this approach assert advantages, including decreased blood loss, operative time, and hospital stay, while providing esthetic results and safety comparable with traditional open craniosynostosis repair. The difficulties inherent in endoscopic visualization may result in complications, however, that could temper enthusiasm for this procedure. The authors report a child in whom a leptomeningeal cyst developed after performance of endoscopic craniosynostosis repair, presumably from an iatrogenic dural laceration. CLINICAL PRESENTATION: A 5-month-old girl with sagittal synostosis underwent endoscopically assisted craniosynostosis repair. By report, the procedure was uneventful and the initial results were acceptable. The authors performed a chart review of their own experience with both endoscopically assisted craniosynostosis repair and traditional open repair. INTERVENTION: Five months after surgery, a pulsating forehead mass developed. Neuroimaging confirmed the diagnosis of a leptomeningeal cyst. The child was referred to our pediatric neurosurgery practice for operative repair. At the time of surgery, a dural defect lying directly under a previous osteotomy site was identified. After uneventful repair and follow-up of more than 1 year, the child is well and is without the development of a clinical seizure disorder or recurrence of her leptomeningeal cyst. CONCLUSION: Unrecognized dural injury combined with an overlying osteotomy in an infant can result in the development of a leptomeningeal cyst. Care must be taken at the time of endoscopic extradural surgery to recognize any inadvertent dural tears and to perform a direct repair at the time of the initial occurrence. Facility with and use of an appropriate endoscope is essential to the safe performance of minimally invasive craniosynostosis surgery.

Arachnoid Cysts↗
PubMed2004

Effect of vagus nerve stimulator magnet on programmable shunt settings.

OBJECTIVE: Vagus nerve stimulators and programmable shunt valves are used in the operative care of epilepsy and hydrocephalus, respectively. Both devices use magnetic fields to activate and program their various settings and functions. The authors conducted several ex vivo trials to better elucidate any interplay between the two systems. METHODS: A pulse generator controller (Cyberonics Corp., Houston, TX) was brought to within 4 cm of Strata programmable shunt valves (Medtronic Neurosurgery, Goleta, CA). Each of five valves was preset to either a low- or high-pressure setting and then challenged with the vagus nerve stimulator generator. Each valve was challenged 20 times, for a total of 100 trials. RESULTS: In 100 trials, 78 inadvertent pressure setting adjustments were recorded. In 46 attempts, the valve pressure was increased, and in 34 attempts, the pressure was decreased. CONCLUSION: This study provides some support to the anecdotal reports of inadvertent adjustments of programmable shunt valves by the external magnetic field created by vagus nerve stimulator pulse generator controllers. Further trials and a double-blind study are necessary to illustrate more clearly the possible relationship of these magnetically controlled neurosurgical devices.

Cerebrospinal Fluid Pressure↗
PubMed2004

Analysis and evolution of head injury in football.

OBJECTIVE: To review head injury in football through historical, anatomic, and physiological analysis. METHODS: We obtained data from a thorough review of the literature. RESULTS: The reported incidence of concussion among high school football players dropped from 19% in 1983 to 4% in 1999. During the 1997 Canadian Football League season, players with a previous loss of consciousness in football were 6.15 times more likely to experience a concussion than players without a previous loss of consciousness (P < 0.05). Players with a previous concussion in football were 5.10 times more likely to experience a concussion than players without a previous concussion (P = 0.0001). With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. CONCLUSION: Significant declines in both the incidence and severity of head injury have been observed. The enhanced safety records in football can be attributed to the application of more stringent tackling regulations as well as the evolving football helmet. The role of a neurosurgeon is critical in further head injury prevention and guidelines in sport.

Adolescent↗
PubMed2004

Birth and evolution of the football helmet.

OBJECTIVE: To review the advent and evolution of the football helmet through historical, physiological, and biomechanical analysis. METHODS: We obtained data from a thorough review of the literature. RESULTS: Significant correlation exists between head injuries and the advent of the football helmet in 1896, through its evolution in the early to mid-1900s, and regulatory standards for both helmet use and design and tackling rules and regulations. With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. Not only is the material used important, but the protective design also proves essential in head injury prevention. Competition among leading helmet manufacturers has benefited the ultimate goal of injury prevention. However, just as significant in decreasing the incidence and severity of head injury is the implementation of newer rules and regulations in teaching, coaching, and governing tackling techniques. CONCLUSION: Helmet use in conjunction with more stringent head injury guidelines and rules has had a tremendous impact in decreasing head injury severity in football. Modifications of current testing models may further improve helmet design and hence further decrease the incidence and severity of head injury sustained while playing football.

Athletic Injuries↗
PubMed2004

The science of shrinking human heads: tribal warfare and revenge among the South American Jivaro-Shuar.

THE PRACTICE OF "head-shrinking" has been the proper domain not of Africa but rather of the denizens of South America. Specifically, in the post-Columbian period, it has been most famously the practice of a tribe of indigenous people commonly called the Jivaro or Jivaro-Shuar. The evidence suggests that the Jivaro-Shuar are merely the last group to retain a custom widespread in northwestern South America. In both ceramic and textile art of the pre-Columbian residents of Peru, the motif of trophy heads smaller than normal life-size heads commonly recurs; the motif is seen even in surviving carvings in stone and shell. Moreover, although not true shrunken heads, trophy heads found in late pre-Columbian and even post-Columbian graves of the region demonstrate techniques of display very similar to those used by the Jivaro-Shuar, at least some of which are best understood in the context of head-shrinking. Regardless, the Jivaro-Shuar and their practices provide an illustrative counterexample to popular myth regarding the culture and science of the shrinking of human heads.

Anthropology, Cultural↗
PubMed2004

Hypothalamic ganglioglioma treated by temporal lobectomy. Case report and review of the literature.

The authors report the case of a hypothalamic ganglioglioma with left-sided temporal lobe extension in an 8-year-old girl who presented with seizures. Other cases of ganglioglioma involving the hypothalamus have been reported in the literature; however, this site of origin is exceedingly rare and worthy of report. Treatment involved medial temporal lobectomy with the hypothalamic component of the tumor remaining untouched. The patient recovered postoperatively with no neurological deficits and was seizure free at 12 months. Neither radio- nor chemotherapy was recommended because of the tumor histology, location, and the patient's age. The authors recommend follow up and surgical treatment for possible tumor recurrence. The prognosis for hypothalamic ganglioglioma is unknown.

Anterior Temporal Lobectomy↗
PubMed2004

Hydrocephalus in children with middle fossa arachnoid cysts.

OBJECT: The optimal management of children with middle fossa arachnoid cysts (MFACs) remains controversial. In this study the authors evaluated the relationship between two preoperative variables, hydrocephalus and nonspecific macrocephaly, in children undergoing fenestration of temporal arachnoid cysts and hydrocephalus-related shunt placement. METHODS: During a 16-year period, 40 children (30 boys and 10 girls) underwent treatment of MFACs. All but one patient experienced either worsening symptoms or progressive serial imaging-documented cyst enlargement. Hydrocephalus was present in six patients and nonspecific macrocephaly in another nine. The mean age at surgery was 66 months (range 1-201 months, median 36 months), and the mean follow-up duration was 54 months (range 6-83 months, median 39 months). All patients presenting with hydrocephalus required placement of a ventriculoperitoneal (VP) shunt as well as cyst fenestration, regardless of which procedure was performed first. Five patients with macroencephaly undergoing initial fenestration required subsequent VP shunt insertion. Complications of cerebrospinal fluid (CSF) diversion were typical. CONCLUSIONS: Patients with hydrocephalus or macrocephaly are likely to require VP shunt placement in addition to cyst fenestration. Children with nonspecific macrocephaly may harbor a latent derangement of CSF circulation.

Adolescent↗
PubMed2004

Deep venous thrombosis in children and adolescents.

OBJECT: The objective of this retrospective review was to identify patients on the pediatric neurosurgical ward with deep venous thrombosis (DVT) to develop diagnostic and treatment-related guidelines. METHODS: The authors performed a retrospective chart review of all cases of DVT presenting to the Children's Hospital between March 1986 and February 1997. Of 32 patients identified, 14 were followed by the neurosurgical service. Current records were additionally evaluated to assess follow-up condition in the patients as well as outcome. Variables included diagnosis, race, age, follow-up duration, outcome, presenting signs/symptoms, involved vessel(s), concurrent disease, diagnostic modalities, and treatment. Patient age ranged from 1 to 16 years (mean 12.6 years, median 15 years). There were five girls and nine boys. Eight DVTs were right sided and six were left sided. Presenting symptoms included swelling of the affected extremity in 11 patients, pain in five, erythema in one, and cardiopulmonary arrest in two. Comorbidities included previous orthopedic procedures in three, brain tumors in two, and sepsis, fracture, pulmonary disease, preexisting coagulation disorders, and brain abscess in one patient each. Eight patients presented with a history of trauma. Two patients had undergone chemotherapy. Diagnostic studies included ultrasonography and venography in one, venography alone in two, computerized tomography (CT) scanning and venography in one, tagged red blood cell studies in one, ultrasonography and CT scanning in one, and ultrasonography alone in eight. In one patient an inferior vena cava filter was placed and one patient was treated with oral warfarin alone. One patient with a brain tumor died while hospitalized. In four patients there was evidence of rheumatological disease in the group of patients not treated neurosurgically. Two patients suffered recurrences during the follow-up period (mean 20 months) In the entire series of 32 patients there were five total deaths. Of these, two patients experienced six recurrences each, and one other patient suffered four recurrences. Of note, none of the recurrences was observed in patients with underlying coagulation disorders. CONCLUSIONS: Children with DVT can experience serious complications in the form of both morbidity and mortality. Although most thrombotic complications have been found in patients with femoral lines, prolonged treatment involving a central line has been found to be a significant predictor of DVT. Multiple treatment modalities currently exist for children with DVT. Low-molecular-weight heparin therapy has many benefits over unfractionated heparin agents and may be more appropriate for the prophylaxis or treatment of children and adolescents with DVT because of its acceptable safety and efficacy. Clinical data for neonates and young children remain incomplete.

Adolescent↗
PubMed2003

Use of elemental iodine for shunt infection prophylaxis.

OBJECTIVE: Elemental iodine (I(2)) can kill a broad spectrum of organisms, including bacteria, fungi, and viruses. Furthermore, it is inexpensive, bacterial resistance is unknown, and allergic reactions are rare. Because of these properties, we wanted to determine the concentration of I(2) that would kill Staphylococcus epidermidis and Staphylococcus aureus without causing injury to the central nervous system, in an attempt to further reduce the rates of shunt infections. METHODS: Bacterial kill studies using S. epidermidis and S. aureus were performed by using Ringer's lactate solution alone or solution containing I(2) at a concentration of 5, 10, 20, 50, 100, or 1000 parts per million (ppm), cefazolin at 1 mg/ml, or bacitracin at 100 units/ml. Twenty-one adult male Wistar rats, in seven groups, underwent a frontoparietal craniectomy. The surfaces of their brains were irrigated for 1 hour with Ringer's lactate solution alone or solution containing I(2) (at the concentrations noted above). After 72 hours of observation, the animals were killed. Their brains were then fixed in formalin, stained with hematoxylin/eosin, and examined. RESULTS: Even with exposure of only 15 seconds to an I(2) solution of 20 ppm, no growth was detected with an inoculum of either bacteria of 100 million. In contrast, the two antibiotics were not nearly as effective as I(2), with kill rates ranging from 19 to 93%. Examination of the rat brains demonstrated no histological changes after subarachnoid exposure to solutions containing 5, 10, 20, or 50 ppm; however, necrosis was observed with concentrations of 100 and 1000 ppm. CONCLUSION: I(2) can be added to irrigation solutions in sufficient concentrations to be bactericidal without causing any central nervous system injury.

Animals↗
PubMed2003

Correction of large (>25 cm(2)) cranial defects with "reinforced" hydroxyapatite cement: technique and complications.

INTRODUCTION: Hydroxyapatite cement is both biocompatible and osteoconductive, and it lacks significant toxic or immunogenic properties, making it an ideal substrate for the repair of cranial defects. However, with its putty-like composition, the repair of large cranial defects can be difficult because significant settling occurs as the cement hardens. We describe a technique in which we use hydroxyapatite cement, reinforced with tantalum mesh and titanium miniplates, for the repair of large (>25 cm(2)) cranial defects. METHODS: After the margins of the cranioplasty are delineated, tantalum mesh is placed under the edges of the defect. Titanium miniplate single-hole bars are used to criss-cross the defect and are then secured to the surrounding bone with screws. The mesh is secured to the bars with 28-gauge stainless steel wire. Hydroxyapatite cement is applied in the defect and contoured appropriately. RESULTS: We performed nine cranioplasties in eight patients ranging in age from 1.5 to 35 years (mean, 12.2 +/- 10.1 yr). The reasons for cranioplasty included cranial defect from prior trauma (n = 4), fibrous dysplasia (n = 2), infected bone flaps (n = 2), and tumor (n = 1). The cranioplasties ranged in size from 40 to 196 cm(2) (mean, 128.3 +/- 56.9 cm(2)). Follow-up ranged from 2 to 33 months (mean, 11.4 +/- 12.8 mo). Two cranioplasty constructs were removed at 1 and 3 months postoperatively owing to infection. CONCLUSION: The use of hydroxyapatite cement with mesh and miniplates provides internal structural support and increased stability of the construct. Although this technique provides an excellent cosmetic result and no evidence to date of bony resorption, the rate of infection is alarmingly high in these large constructs.

Adolescent↗
PubMed2003

Neonatal subgaleal hematoma causing brain compression: report of two cases and review of the literature.

OBJECTIVE AND IMPORTANCE: Neonatal subgaleal hematomas (SGHs) are infrequent but underdiagnosed collections of blood beneath the galea, often caused by vacuum delivery. With massive bleeding into the subgaleal space, exsanguination and hypovolemic shock can cause death in 20 to 60% of newborn infants. We report the first two known patients with extracranial cerebral compression caused by SGH. Also, the surgical evacuation of neonatal SGH has not been described previously. CLINICAL PRESENTATION: One patient was a full-term boy who was delivered via vacuum extraction after an uncomplicated pregnancy. Within a few hours, he developed an expanding fluid collection of the scalp and disseminated intravascular coagulation and shock requiring intubation, inotropic support, and blood transfusions. His head circumference grew from 33 cm at birth to 42 cm. He became progressively lethargic and developed posturing movements. Computed tomography of the head revealed a massive SGH causing gross overlapping of the cranial sutures and diffuse cerebral edema. The other patient was a full-term boy delivered via cesarean section after an unsuccessful attempt at vacuum extraction and forceps delivery. The initial head circumference was 34 cm. Within a few hours, he developed an expanding fluid collection of the scalp and became progressively lethargic with posturing. Magnetic resonance imaging of the head revealed a massive SGH with cranial compromise and diffuse cerebral edema. INTERVENTION: Both children had radiographic features indicative of elevated intracranial pressure as well as neurological decompensation. The first patient was taken to the operating room, and the hematoma was evacuated through a small scalp incision. Initially, approximately 150 ml of blood was removed, and a Jackson-Pratt drain diverted another 200 ml of blood during the next 2 days. The infant made a good recovery. In the second case, the patient remained too unstable for operative intervention and died. CONCLUSION: Extracranial cerebral compression represents another way by which neonatal SGH may jeopardize the infant's life. Management consists of measures to correct hypovolemic shock and disseminated intravascular coagulation, as well as surgical intervention to control elevated intracranial pressure.

Adolescent↗
PubMed2003

Microsurgical keyhole approach for middle fossa arachnoid cyst fenestration.

OBJECTIVE: The optimal surgical treatment for symptomatic temporal arachnoid cysts is controversial. Therapeutic options include cyst shunting, endoscopic fenestration, and craniotomy for fenestration. We reviewed the results for patients who were treated primarily with craniotomy and fenestration at our institution, to provide a baseline for comparisons of the efficacies of other treatment modalities. METHODS: A retrospective review of data for 50 children who underwent keyhole craniotomy for fenestration of temporal arachnoid cysts between 1994 and 2001 was performed after institutional review board approval. During that period, the first-line treatment for all symptomatic middle fossa arachnoid cysts was microcraniotomy for fenestration. Microsurgical dissection to create communications between the cyst cavity and basal cisterns was the goal. All patient records were reviewed and numerous variables related to presentation, cyst size and classification, treatment, cyst resolution, symptom resolution, follow-up periods, and cyst outcomes were recorded. RESULTS: Fifty temporal arachnoid cysts in 50 treated patients were identified. The average age at the time of surgery was 68 +/- 57.2 months. The follow-up periods averaged 36 months. There were 34 male and 16 female patients in the series. Twenty-six cysts were on the left side. Indications for surgery included intractable headaches (45%), increasing cyst size (21%), seizures (25%), and hemiparesis (8%). The symptoms most likely to improve were hemiparesis (100%) and abducens nerve palsies. Headaches (67%) and seizure disorders (50%) were less likely to improve. Nine patients exhibited progressive increases in cyst size in serial imaging studies. Those patients were monitored for a mean of 40 +/- 23 months before intervention. In the entire series, 82% of patients demonstrated decreases in cyst size in serial imaging studies. Of those patients, 18% demonstrated complete cyst effacement. Overall, 83% of patients with Grade II cysts and 75% of patients with Grade III cysts exhibited evidence of decreases in cyst size in long-term monitoring. Two patients required shunting after craniotomy (4%). Hospital stays averaged 3.4 days. Total surgical times averaged 115 minutes. No significant blood loss occurred (5-50 ml). Complications included spontaneously resolving pseudomeningocele (10%), transient Cranial Nerve III palsy (6%), cerebrospinal fluid leak (6%), subdural hematoma (4%), and wound infection (2%). CONCLUSION: A microsurgical keyhole approach to arachnoid cyst fenestration is a safe effective method for treating middle fossa cysts. This procedure can be performed with minimal morbidity via a minicraniotomy. Compared with an endoscopic approach, better control of hemostasis can be obtained, because of the ability to use bipolar forceps and other standard instruments. The operative time and length of hospital stay were not excessively increased.

Adolescent↗
PubMed2003

The assassination of President John F Kennedy: a neuroforensic analysis--part 1: a neurosurgeon's previously undocumented eyewitness account of the events of November 22, 1963.

SUBSTANTIAL LITERATURE EXISTS on the assassination and subsequent pathological examination of President John F. Kennedy. The Warren Report, the United States Government's official report on the assassination, instead of providing definitive answers on the precise cause of President Kennedy's death, sparked intense and on-going debate. Since the publication of the Warren Report in September 1964, many issues have been woven into a wide array of theories concerning the assassination. One element continues to generate debate, namely, the exact sites of the wounds that President Kennedy sustained. A neuroforensic analysis of the wounds, from the perspective of the neurosurgeon, would establish a reasonable hypothesis for the mechanics of the shooting. Eyewitness accounts of the events surrounding the assassination represent one critical source of data for such an analysis. This report provides a previously undocumented neurosurgeon's eyewitness account of what transpired in Trauma Room 1 of Parkland Memorial Hospital on November 22, 1963.

Autopsy↗