Biomedical subjects
Publications and source records attributed to John C Wellons.
The authors report a patient with type II split cord malformation (SCM) and Klippel-Feil syndrome (KFS). Considering our review of the medical literature and present case report, we believe lumbar SCM and KFS in the same patient not to be coincidental findings but rather embryologically related entities. We propose that KFS in at least one of its phenotypes represents a forme fruste of occult spinal dysraphism.
There are scant data in the literature regarding distances from the midline to the suboccipital segment of the vertebral artery, and to our knowledge, none addressing this measurement in the pediatric population. This study seeks to establish age-related distances (Y) from the laterally placed vertebral artery to the midline at the level of the posterior arch of the atlas in children. Measurements from the midline to the most medial portion of the vertebral artery at the level of the posterior arch of the atlas were made in 50 children who underwent CT imaging of the cervical spine. For all left sides, Y = 12-23 mm (mean 17 mm). For all right sides, Y = 10-25 mm (mean 17.5 mm). For girls, Y = 12-16 mm (mean 12.7 mm) for left sides and Y = 12-25 mm (mean 18.5 mm) for right sides. For boys, Y = 12-20 mm (mean 16 mm) for left sides and Y = 10-21 mm (mean 16.7 mm) for right sides. We have found that the most medial portion of the vertebral artery from the midpoint of the posterior arch of the atlas for all ages was approximately 17 and 17.5 mm for left and right sides, respectively. This distance was generally less for left sides, except in the 16-19 years age group. However, as a group, this distance did not vary more than 2.8 mm between left and right sides. These data should assist the neurosurgeon who operates in the suboccipital region in children.
OBJECTIVE: Accounts of bony human horns originating from the cranium are found peppered throughout the early medical literature. This study reviews the extant literature regarding these entities to elucidate their authenticity. METHODS: We reviewed both historical and current literature as well as osteological material from our anatomy laboratories for accounts or observations of bony outgrowths of the calvaria in humans. RESULTS: Human horns seem to be mentioned more frequently in the historical literature and are documented primarily with drawings. Moreover, from early accounts, it is often difficult to distinguish true large bony outgrowths from scalp excrescences. Only two cadaveric specimens from our laboratory were noted to have small anomalous bony protuberances, one on the occiput and one on the frontal bone. CONCLUSION: With the lack of either photographic or extreme dry specimen evidence of such human horns, we would propose that benign calvarial tumors, such as osteomas, may have initiated speculation that such entities, i.e., horns, exist in humans but that scalp lesions, exaggeration, legend, and religious beliefs have historically propagated these entities to a mythical status. In addition, early surgical intervention and changes in nomenclature may have also decreased the frequency of such sightings. Finally, many early descriptions have not been repeated in recent history, even in third-world countries lacking advanced medical care.
OBJECTIVE: Avoidance of injury to the thoracic duct during neurosurgical procedures involving the cervical region depends on a working knowledge of its location. This study evaluates superficial anatomic landmarks for the cervical portion of the thoracic duct that may be encountered in neurosurgery of the neck. METHODS: Fifteen dissections of human cadavers were performed to study the relationship between the proximal thoracic duct and superficial landmarks (e.g., the cricoid cartilage and sternal notch of the manubrium). RESULTS: The cervical portion of the thoracic duct was found to be approximated by a roughly 4.4-cm(2) region in the left supraclavicular area beginning approximately 2.0 cm lateral to the midline and 3.5 cm superior to the sternal notch, extending superiorly to a point roughly 3.5 cm from the midline and 2.5 cm inferior to the cricoid cartilage, and terminating within the venous system at a point approximately 4.5 cm lateral to the midline and 3.0 cm superior to the sternal notch. CONCLUSION: Through an increased appreciation for its location, injury to the thoracic duct may be minimized.
We present the progressive clinical course of a child with myelopathy attributable to cervical spine abnormalities associated with Larsen's syndrome. After anterior and posterior cervical fusion, his preoperative symptoms of weakness, gait dysfunction, and hyperreflexia have improved at 9-month follow-up. The progressive course and importance of early referral and intervention should be of interest to the general pediatric community.
OBJECT: The quantitative analysis of odontoid process angulation has had scant attention in the Chiari I malformation population. In this study the authors sought to elucidate the correlation between posterior angulation of the odontoid process and patients with Chiari I malformation. METHODS: Magnetic resonance images of the craniocervical junction obtained in 100 children with Chiari I malformation and in 50 children with normal intracranial anatomy (controls) were analyzed. Specific attention was focused on measuring the degree of angulation of the odontoid process and assigning a score to the various degrees. Postoperative outcome following posterior cranial fossa decompression was then correlated to grades of angulation. Other measurements included midsagittal lengths of the foramen magnum and basiocciput, the authors' institutions' previously documented pB-C2 line (a line drawn perpendicular to one drawn between the basion and the posterior aspect of the C-2 body), level of the obex from a midpoint of the McRae line, and the extent of tonsillar herniation. Higher grades of odontoid angulation (retroflexion) were found to be more frequently associated with syringomyelia and particularly holocord syringes. Higher grades of angulation were more common in female patients and were often found to have obices that were caudally displaced greater than three standard deviations below normal. CONCLUSIONS: These results not only confirm prior reports of an increased incidence of a retroflexed odontoid process in Chiari I malformation but quantitatively define grades of inclination. Grades of angulation were not found to correlate with postoperative outcome. It is the authors' hopes that these data add to our current limited understanding of the mechanisms involved in hindbrain herniation.
OBJECT: To the best of the authors' knowledge, no quantitative analysis of the atlantoaxial interlaminar distance in flexion (ILD) in children exists in the medical literature. In this study they sought to determine the age-matched relationship between the posterior elements of the atlas and axis in children in cervical spine flexion, to be used as an adjunct to the atlantodental interval in common clinical use. METHODS: Lateral radiographs of the cervical spine in full flexion were analyzed in 74 children. The atlantoaxial ILD was defined as the distance between a midpoint of the anterior cortices of the atlantal and axial posterior arches. The mean ILD for the entire group was 19 mm (range 8-30 mm). No significant difference was seen between male and female patients (p = 0.084). When stratified by age, the mean ILD was 12.3 +/- 3 mm (15 cases) in children age 3 years or younger and 20.5 +/- 4.7 mm (59 cases) in children age older than 3 years. Further stratification of the groups yielded a mean ILD of 10.4 +/- 1.4 [eight cases]) in children age 1 to 2 years, and 14.4 +/- 4.7 mm (seven cases) in children age 3 years. In children older than 3 years of age the mean ILD was consistently approximately 20 +/- 5 mm regardless of age. CONCLUSIONS: Rapid, safe, and accurate diagnosis of the cervical spine is essential in critical care. Knowledge of the distance between the posterior elements of the atlas and axis in flexion should enhance the clinicians' (those who clear cervical spines) ability to diagnose accurately atlantoaxial instability on lateral radiographs obtained in flexion.
CASE REPORT: We report a pediatric patient with encephalocele, lipomeningomyelocele, and Chiari I malformation. DISCUSSION: We also review the extant medical literature regarding associations between these three entities. We propose that the combination of these three pathologies, which is reported here for the first time, is not serendipitous but rather a low-frequency association. CONCLUSIONS: After a literature review, we speculate that encephalocele and lipomeningomyelocele most probably occur by mechanisms similar to those that produce encephalocele and meningomyelocele and that the tonsillar ectopia in our patient is due to an abnormally small posterior cranial fossa resulting from the lack of neural tissue within the cranium at critical times during development or has its genesis, as some encephaloceles may, in inappropriate paraxial mesoderm formation.
INTRODUCTION: Sagittal synostosis has been found to occur in families at a low frequency. All previous reports of sagittal synostosis in twins have been of males. CASE REPORT: We now report a case of female twins concordant for sagittal synostosis. CONCLUSION: Our hopes are that this information will further our understanding of the genetics of sagittal synostosis not only in single births but also in that of twins.
OBJECTIVE: Cadaveric studies of the blood supply to the human cervical sympathetic chain and ganglia are lacking in the English literature. This study seeks to elucidate the gross blood supply of the cervical sympathetic chain so as to avoid surgical disruption of these vessels and thus decrease the risk of vascular insufficieny and subsequent dysfunction of thoracolumbar autonomic outflow to the head and neck. METHODS: Twelve (24 sides) human cadavers (8 male and 4 female) were dissected and their brachiocephalic veins, internal carotid arteries, and vertebral arteries cannulated. Red and blue latex was injected into the arteries and veins respectively. Dissection of the neck was carefully performed and the blood supply of the cervical sympathetic chain identified. RESULTS: The primary arterial supply to the sympathetic chain and ganglia were from superior to inferior the ascending pharyngeal, ascending cervical, thyrocervical trunk, and supreme intercostal arteries. The primary venous drainage of these structures was primarily by direct posterior branches into the internal jugular vein. In addition, we have found an area at the junction of the lower two-thirds and upper one-third of the neck, which is deficient in blood supply (both arterial and venous). CONCLUSIONS: Although sympathetic injury is a rare consequence of cervical operations, the current data should be useful to the surgeon who operates in the cervical region so as to avoid potential complications from disruption of the primary blood supply of the cervical sympathetic chain and ganglia. Also, future techniques of selective iatrogenic disruption of the blood supply to portions of these structures e.g. stellate ganglion may be helpful in treating entities such as hyperhydrosis.
OBJECTIVE: We report the control of hydrocephalus in children with presumed tectal plate gliomas by the use of endoscopic third ventriculostomy (ETV). METHODS: The hospital records, office charts, and imaging studies from children who underwent ETV at the Children's Hospital of Alabama were reviewed. Thirteen children with the diagnosis of tectal plate glioma and hydrocephalus were identified. ETV was the primary therapy instituted for all but one of these children. Successful treatment outcome was defined as shunt freedom, improvement in symptoms, and reduced ventricular size. RESULTS: Thirteen children underwent a total of 15 ETVs, and all children were shunt-free at their most recent follow-up examinations. One child underwent successful secondary ETV, one child underwent shunt removal concomitant with the initial ETV, and one child underwent shunt removal concomitant with secondary ETV. Symptoms and signs resolved in all patients. All postoperative cranial imaging studies revealed normal or reduced ventricular size as compared with preoperative cranial imaging scans. The median follow-up period was 31 months. CONCLUSION: In our surgical experience, ETV has been uniformly successful in the management of hydrocephalus caused by tectal plate gliomas in children. ETV should be considered the treatment of choice for hydrocephalus in pediatric patients with tectal plate gliomas.
Complications of posterior cranial fossa decompression for Chiari malformations are uncommon. We present three patients who developed infratentorial supracerebellar hygromas causing acute hydrocephalus after posterior cranial fossa decompression.
INTRODUCTION: The removal of the choroid plexus from the lateral ventricles was attempted by Dandy in the early 20th century but later discarded as complications arose and other methods of cerebrospinal fluid (CSF) diversion were introduced. We compare our experience with a variation of this operation to CSF diversion in patients with hydranencephaly or near hydranencephaly. METHODS: The hospital and office charts of patients with a diagnosis of hydranencephaly were reviewed from the two institutions spanning the career of the senior author. Thirteen patients were identified, of whom 9 underwent CSF diversionary procedures (group A) and 4 underwent choroid plexectomy (group B). RESULTS: The mean number of reoperations (2 in group A, 0 in group B), neurosurgical readmissions (1.5 in group A, 0 in group B) and days of hospitalization related to neurosurgical readmissions (43.5 in group A, 0 in group B) were all less in patients who underwent choroid plexectomy. The total incidence of complications related to surgery was also lower in this group (7 in group A, 0 in group B). CONCLUSION: In our experience, choroid plexectomy in patients with hydranencephaly reduces the incidence of reoperation and readmission, the number of days of hospitalization related to the surgical procedure and the total number of complications in comparison to patients undergoing CSF diversion. Further neurosurgical intervention is minimized as is the financial burden from multiple emergency department visits and radiological procedures for shunt evaluation. Choroid plexectomy is a viable alternative to CSF diversion in patients with hydranencephaly and a rapidly enlarging head. It avoids the chronic issues and complications surrounding CSF diversion in this difficult group of patients.
The horizontal sacrum has never been described as an indicator of a tethered spinal cord following myelomeningocele closure. We retrospectively analyzed 30 children with a myelomeningocele for this progressive change and its correlation with symptoms. At least two lateral radiographs over time were examined and the lumbosacral angle (LSA) was measured. We found that the majority of these children had an LSA that was greater than would be expected in patients with late and decreased ambulatory abilities. Also, we observed that the LSA was often inappropriately increased at the time many of these patients presented with symptoms indicative of a tethered spinal cord. We hypothesize that the LSA in this group of children is altered by a tethered spinal cord and that the horizontal nature of the sacrum may predate the clinically appreciable symptoms of a tethered spinal cord.
BACKGROUND: Innovations in shunt technology and neuroendoscopy have been increasingly applied to shunt management. However, the relative life span of shunts and the etiology of shunt failure have not been characterized recently. METHODS: We reviewed the records of all shunting procedures at our institution between January 1992 and December 1998. Independent predictors of shunt failure were analyzed via multivariate Cox regression analysis in 836 shunting procedures. Independent predictors of the etiology of failure (infection, proximal obstruction, distal malfunction) were analyzed via multivariate logistic regression analysis in the 383 shunts which failed. RESULTS: A total of 353 pediatric patients underwent 308 shunt placements and 528 revisions. The risk (hazard ratio; HR) of shunt failure decreased as a function of time in both primary placements and revised shunts. In failed shunts, the odds of infection decreased 4-fold per year of shunt function, while the odds of distal malfunction increased 1.45-fold per year. Increasing number of shunt revisions (HR 1.31, p < 0.05), decreasing patient age in years (HR 1.04, p < 0.001), gestational age <40 weeks (HR 2.15, p < 0.001) but not the etiology of hydrocephalus were associated with an increased risk of shunt failure. Revisions versus primary placements, Dandy-Walker cysts and gestational age <40 weeks were independently associated with proximal, distal and infectious causes of failure, respectively. CONCLUSIONS: The long-term shunt revision rates observed here are similar to those reported over the past 2 decades. Shunt life span remains poorer in shunt revisions and in younger patients. Patient characteristics may suggest a specific risk and mechanism of failure, aiding in the long-term management of shunted hydrocephalus.
Dolichoodontoid is defined as hypertrophy of the apical portion of the odontoid process of the axis. We report the first case of a dolichoodontoid process in a pediatric patient with other congenital anomalies. This rare entity has had three previous citations in the literature. Our patient presented with scoliosis in which subsequent MRI demonstrated a Chiari I malformation, a small thoracic syrinx and a dolichoodontoid process. The diagnosis of this malformation should be entertained in cases of craniocervical anomalies.
There has been almost no evaluation or discussion of the symmetry of tonsillar ectopia in the medical literature. We measured the degree of left and right tonsillar herniation in 42 pediatric patients with a symptomatic Chiari I malformation and made clinical/radiological correlations. 18% of all patients with tonsillar asymmetry had clinical symptoms or physical findings referable to the inequality of their hindbrain herniation. In addition, 95% of patients with a coexisting syringomyelia had a right cerebellar tonsillar herniation greater than the left. We hypothesize that slight differences in posterior cranial fossa morphology may physically allow for greater unilateral herniation of the left or right cerebellar tonsil, which may be manifested in a patient's clinical presentation.