Biomedical subjects

John C Wellons

Publications and source records attributed to John C Wellons.

At least 37 records · Page 2Linked to original sources

PubMed2005

Unusual findings during abdominal placement of a ventriculoperitoneal shunt: report of three cases.

The authors present three cases of infants born with myelodysplasia. Each infant underwent closure of a myelomeningocele and within 2 to 4 days placement of a ventriculoperitoneal (VP) shunt. In each case, on opening the peritoneal cavity, the authors observed egress of a dark or creamy dark fluid. None of the patients had a history of abdominal birth trauma. The decision was made to continue the procedures and send samples of the unusual fluids to the laboratory for culture and analysis. The cultures proved to be nondiagnostic and the characteristics of the fluid samples were most consistent with those of blood-tinged chyle. The authors hypothesize that, occasionally, the mechanical tautness that is created with repair of myelomeningoceles is sufficient to rupture small lymphatic vessels and accompanying blood vessels of the abdomen. An alternative hypothesis is that abdominal compression due to closure of the myelomeningocele may temporarily compress the liver, leading to raised intraportal pressures and resulting in weeping of chyle from the gastrointestinal tract. This abnormal fluid accumulation did not lead to chronic ascites, VP shunt infection, or dysfunction at long-term follow-up examination and abdominal visceral function has not been an issue.

Ascitic Fluid↗

PubMed2005

Supraplacode spinal cord transection in paraplegic patients with myelodysplasia and repetitive symptomatic tethered spinal cord.

OBJECT: The authors describe the technique of transecting the spinal cord in children born with myelomeningocele who have undergone multiple detherings and are functionally paraplegic. METHODS: The authors' technique involves identifying the neural placode and sectioning the normal spinal cord just superior to this site. No postoperative complications have been identified in 14 patients undergoing this procedure over an 11-year period. No patient at last follow up was found to have symptoms referable to a tethered spinal cord. The advantage of this procedure is to excise the normally pia-coated cord, which is unlikely to retether compared with the neural placode, which is often covered with scar tissue and does not have a well-formed pial surface--hence, predisposing it to frequent dorsal adhesions. CONCLUSIONS: The authors believe that this technique is of benefit in a small, carefully selected group of myelodysplastic patients with repetitive tethering of the spinal cord.

Adolescent↗

PubMed2005

Anatomical landmarks for the lumbar plexus on the posterior abdominal wall.

OBJECT: Reports describing surgical landmarks with which to identify the branches of the lumbar plexus found on the posterior abdominal wall are lacking in the English-language literature. METHODS: The authors examined 22 sides from six female and five male cadavers. Measurements were made between the branches of the lumbar plexus and various bone landmarks such as the midline vertebral bodies, supracristal plane--a horizontal line connecting the superior-most aspect of the left and right iliac crests approximating the LA-5 vertebrae--and anterior superior iliac spine (ASIS). The mean distances from the midline and as they emerged through or lateral to the psoas major muscle to the subcostal, iliohypogastric, ilioinguinal, lateral femoral cutaneous, genitofemoral, and femoral nerves, were 5.5, 6, 6.5, 6, 4.5, and 4.5 cm, respectively. At a vertical line through the midpoint between the ASIS and the midline, the subcostal, iliohypogastric, and ilioinguinal nerves were superior to the supracristal plane at mean distances of 8, 4, and 5 cm, respectively. Inferior to the supracristal plane and in a vertical line through a midpoint between the ASIS and the midline, the lateral femoral and femoral nerves were found to have mean distances of 5 and 5.5 cm, respectively. The obturator nerve had a mean distance of 3 cm lateral to the midline. Additionally, the lateral femoral cutaneous nerve had a mean distance of 1.5 cm inferomedial to the ASIS. CONCLUSIONS: A good working knowledge of the locations and anatomy of the nerves of the lumbar plexus on the posterior abdominal wall is necessary for the surgeon who operates in this region. The measurements provided herein will aid the surgeon who wishes to expose or avoid these nerves, thus precluding injury.

Abdominal Wall↗

PubMed2005

Superficial landmarks for the spinal accessory nerve within the posterior cervical triangle.

OBJECT: The spinal accessory nerve (SAN) within the posterior cervical triangle (PCT) is the most commonly iatrogenically injured nerve in the body. Nevertheless, there is a paucity of published information regarding superficial landmarks for the SAN in this region. Additional identifiable landmarks of this nerve may assist the surgeon in identifying it for repair, use of it in peripheral nerve neurotization, or avoiding it as in proximal brachial plexus repair. The present study was undertaken to provide reliable superficial landmarks for the identification of the SAN within the PCT. METHODS: The PCT was dissected in 30 cadaveric sides. Measurements were made between the SAN and surrounding landmarks. The mean distances between the entry site of the SAN into the trapezius and a midpoint of the clavicle, mastoid process, acromion process, and lateral aspect of the sternocleidomastoid (SCM) muscle were 6, 7, 5.5, and 3.5 cm, respectively. The mean distances between the angle of the mandible and the mastoid process and the exit point of the SAN from the posterior border of the SCM muscle were 6 and 5 cm, respectively. The mean width and length of the SAN were 3 and 3.5 cm, respectively. CONCLUSIONS: It is the authors' hope that these data will aid those who may need to locate or avoid the SAN while undertaking surgery in the PCT and thus decrease morbidity that may follow manipulation of this region.

Accessory Nerve↗

PubMed2004

Russell Silver syndrome and tethered spinal cord.

CASE REPORT: We report a 20-year-old male with Russell Silver syndrome and tethered cord syndrome. This patient presented with non-painful scoliosis. MRI demonstrated a conus medullaris at the superior aspect of the L3 vertebral body. Axial images demonstrated no fat within the filum terminale. There was a horizontal sacrum. The patient had no cutaneous stigmata over the lumbosacral spine indicative of occult spinal dysraphism. At operation, the filum terminale was found to be quite large at approximately 5.0 mm in diameter. Grossly, the filum was found to have several large vessels both anterior and posterior to it. Following transection of the filum the distal cord was noted to withdraw cephalad indicating caudal traction. DISCUSSION: We believe this to be the first report of Russell Silver syndrome in conjunction with tethered cord syndrome. Following additional reports, Russell Silver syndrome may be added to the differential diagnoses for tethered cord syndrome.

Adult↗

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

Left-sided vagus nerve stimulation decreases intracranial pressure without resultant bradycardia in the pig: a potential therapeutic modality for humans.

INTRODUCTION: The medical literature is lacking in data regarding intracranial pressure in an animal model with concomitant vagus nerve and spinal cord stimulation. METHODS: Ten pigs were anesthetized and placed in the supine position and an intracranial pressure monitor was inserted. Each study animal had a small laminectomy performed in the lumbar region and the left vagus nerve exposed within the carotid sheath. Intracranial pressure was monitored for 3 h in all animals. Eight animals at the end of 3 h of monitoring underwent vagus nerve stimulation and or spinal cord stimulation. Study and control animals had their intracranial pressure monitored for an additional 1 and 2 h respectively. RESULTS: Following vagus nerve stimulation, all animals had significant (p<0.05) decreases in their intracranial pressure with a lasting effect of 15-35 min (mean 18.5 min). No significant change in blood pressure was noted during stimulation of the vagus nerve. After spinal cord stimulation all animals responded with acute increases in their intracranial pressure (p<0.05). CONCLUSIONS: Left vagus nerve stimulation reliably decreases intracranial pressure in the pig. The mechanism of this action remains unclear and does not appear to be due to resultant bradycardia. Conversely, stimulation of the upper lumbar spinal cord increases intracranial pressure with simultaneous increases in heart rate. Following additional studies and with close observation of cerebral perfusion pressure, we believe that left vagus nerve stimulation may represent a novel adjunctive therapy for decreasing elevated intracranial pressure in posttraumatic human patients with head injuries. Additionally, according to this animal data, minimizing spinal cord stimulation should be considered in the acute setting following head injury so as to minimize iatrogenic elevation of intracranial pressure.

Animals↗

PubMed2004

Degree of tectal beaking correlates to the presence of nystagmus in children with Chiari II malformation.

INTRODUCTION: Tectal beaking is a common finding in children born with a myelomeningocele. Quantitation of the presence or absence of this finding correlated with normal or abnormal eye movements is lacking in the medical literature. MATERIALS AND METHODS: We prospectively evaluated 50 children in our multidisciplinary spina bifida clinic. Each child was observed for the presence or absence of nystagmus at rest or with extraocular movement. Grades of nystagmus and severity of tectal beaking (Types I-III) on MRI were then correlated. RESULTS: Overwhelmingly, children with greater dysmorphology of the mesencephalic tectum were most likely to have nystagmus. Higher grades of nystagmus were associated with Type III tectal beaking. CONCLUSIONS: We have demonstrated that there is a correlation between the presence and severity of nystagmus and the severity of tectal beaking and have quantified this association in patients with the Chiari II malformation. This information may act as a guide in predicting which children with the Chiari II malformation will have significant nystagmus. These data may aid the clinician in the interpretation of oculomotor abnormalities in this cohort of patients.

Adolescent↗

PubMed2004

Split cord malformation and situs inversus totalis: case report and review of the literature.

INTRODUCTION: Situs inversus is a rare condition of visceral transposition in which the spinal axis is rarely affected. CASE REPORT: The authors report a patient with situs inversus totalis and Type II split cord malformation. The patient had no symptoms and presented with scoliosis. CONCLUSIONS: Recent compelling evidence from animal models and human case reports has lead to hypotheses that defects of the midline and laterality defects (e.g., situs inversus) are etiologically related. Confirmation from additional case reports of situs inversus and split cord malformation could prove useful in determining a genetic locus for split cord malformations or implicating various chemical agents that are known to produce situs inversus as potential causative factors in the production of split cord malformations.

Child↗

PubMed2004

Fenestration of the superior medullary velum as treatment for a trapped fourth ventricle: a feasibility study.

We developed a novel approach for fenestration of the trapped fourth ventricle utilizing the superior medullary velum (valve of Vieussens). Trapped fourth ventricles, which are seen often in the pediatric hydrocephalic population, are troublesome entities surgically. A right burr hole was carried out in 10 adult cadavers with no gross intracranial pathology and the superior medullary velum was fenestrated to the quadrigeminal cistern with the aid of an endoscope. This technique was carried out easily in all cadaveric specimens. With endoscopy, no vascular insult was appreciated either before or after fenestration of the superior medullary velum. These preliminary findings demonstrate that fenestration of the superior medullary velum may provide a good alternative to the present therapy of shunting trapped fourth ventricles, a therapy wrought with complications.

Aged↗

PubMed2004

Sacral tuberculosis: a case report and review of the literature.

BACKGROUND: We present a patient with a heterogeneously enhancing lesion within the body of the sacrum and the sacral canal. Sacral tuberculosis (TB) was suspected because of a history of familial exposure. Few cases isolated to the sacrum have been reported in the literature. The characteristic histopathologic and magnetic resonance imaging (MRI) findings are also presented. CASE DESCRIPTION: A 31-year-old African-American male presented with an 8-month history of lower back pain radiating into his legs as well as numbness and weakness of the right foot. His history revealed PPD conversion following an exposure to active pulmonary TB 3 years prior for which he received 6 months of isoniazid prophylaxis. An MRI scan revealed a large heterogeneously enhancing lesion involving the sacrum with extension into the sacral canal. The patient underwent computed tomography (CT)- guided needle biopsy of the sacral lesion. Cytopathologic examination revealed caseating granulomas. Acid-fast bacilli cultures were positive for Mycobacterium tuberculosis. He was placed on a 6-month course of isoniazid, rifampin, pyrazinamide, and ethambutol. At 3-month follow-up, his examination and symptoms had improved. CONCLUSIONS: Sacral TB is an extremely rare cause of lower back pain with radiation into the lower extremities. TB should always be considered in the differential diagnosis of isolated sacral masses, especially in light of today's increasing multidrug resistance and immunosuppressed population.

Adult↗

PubMed2004

Duane's syndrome and giant parietal foramina.

We report a 14-month-old male with Duane's syndrome and bilateral parietal calvarial defects. This child had no other known medical conditions. The Duane's syndrome involved the left eye. Imaging was demonstrative of bilateral enlarged parietal foramina. We believe this to be the first reported case of simultaneous Duane's syndrome and bilateral giant parietal foramina. Further case reports of our current association are required to determine if these simultaneous findings are spurious or a low-frequency association.

Duane Retraction Syndrome↗

PubMed2004

Syringomyelia in twin brothers discordant for Chiari I malformation: case report.

Familial syringomyelia outside of trauma, tumor, or infection has been reported. Cases are presented that highlight the possible connection between familial syringomyelia and the Chiari 0 malformation. We report on 11-year-old twin brothers both with syringomyelia. Magnetic resonance imaging further revealed that one brother had Chiari I malformation and the other had Chiari 0 malformation. Both underwent posterior fossa decompression with radiologic improvement of their syringes. These case reports lend credence to earlier reports of improvement in syringomyelia following posterior fossa decompression in the absence of Chiari I malformation, the so-called Chiari 0 malformation. In addition, these case reports should influence the manner in which familial syringomyelia without tonsillar ectopia is defined and addressed, that is, posterior fossa decompression versus shunting of the syrinx, thereby addressing the potential cause of the syringomyelia and not only the enlarged cavity itself.

Arnold-Chiari Malformation↗

PubMed2004

Refining the staging evaluation of pineal region germinoma using neuroendoscopy and the presence of preoperative diabetes insipidus.

Treatment strategies for CNS germinoma are currently evolving. Current approaches include reducing the volume and dose of radiation by adding pre-irradiation chemotherapy. Very accurate staging is necessary with such an approach to prevent failures. Eight consecutive patients with pineal germinoma at one institution underwent endoscopic surgery for tumor biopsy, direct visualization of the third ventricular region, and third ventriculostomy for those with hydrocephalus. All patients were treated with 4 cycles of chemotherapy. Conformal field radiation therapy followed, with the dose to the tumor bed dependent on the response to chemotherapy. Patients who had MRI, endoscopic, or cerebrospinal fluid evidence of multicentric or disseminated disease also received craniospinal radiation. Six patients had diabetes insipidus (DI) at presentation. All 6 had tumor studding the floor of the third ventricle on endoscopic visualization, while only 4 of those patients had MRI evidence of disease in that region. All patients have completed therapy and are alive, with no evidence of disease at median follow-up of 31.5 months from diagnosis. Direct endoscopic visualization of the third ventricular region may be more sensitive than MRI for evaluating the presence of suprasellar disease and appears to add important information. This parameter should be added to the staging evaluation when feasible. In this series, the presence of DI was 100% predictive of suprasellar disease, even when the MRI was negative for involvement of that region. Patients should be evaluated for DI as part of the initial staging, and if it is present, the patients should be treated for suprasellar disease regardless of MRI findings.

Adolescent↗

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

Isolated flat capillary midline lumbosacral hemangiomas as indicators of occult spinal dysraphism.

OBJECT: Historically, cutaneous stigmata representative of occult spinal dysraphism (OSD) have included lumbar hemangiomas. Frequently, this skin change is found in conjunction with other cutaneous alterations such as dermal sinus tracts and subcutaneous lipomas. Debate has recently surrounded the question of whether these skin changes in isolation might indicate underlying spinal disease. The authors reviewed their experience in their most recent 120 cases in which OSD was diagnosed. METHODS: The authors retrospectively reviewed records obtained in 120 patients with OSD. They found that many of the patients reviewed harbored only a flat capillary hemangioma as an indicator of OSD. In 21 patients (17.5%) with only midline lumbosacral flat capillary hemangiomas, underlying OSD was present. No single variety of OSD had a higher incidence of association with this single cutaneous stigma. CONCLUSIONS: Based on their experience, the authors recommend magnetic resonance (MR) imaging evaluation in cases involving this skin lesion in isolation to discern the potential for surgically significant spinal cord anomalies. Prospective studies are now needed to examine MR images obtained in all children with this lesion in the midline lumbosacral spine and assess for OSD.

Child↗

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↗