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Biomedical subjects

D C Armstrong

Publications and source records attributed to D C Armstrong.

At least 19 recordsLinked to original sources
PubMed2001

Presumed pre- or perinatal arterial ischemic stroke: risk factors and outcomes.

A subgroup of children with arterial ischemic stroke in the pre- or perinatal period present with delayed diagnosis. We identified 22 children who met the following criteria: (1) normal neonatal neurological history, (2) hemiparesis and/or seizures first recognized after two months of age, and (3) computed tomography or magnetic resonance imaging showing remote cerebral infarct. Laboratory evaluations included protein C, protein S, antithrombin, activated protein C resistance screen (APCR), Factor V Leiden (FVL), prothrombin gene defect, methylene tetrahydrofolate reductase variant (MTHFR), anticardiolipin antibody (ACLA), and lupus anticoagulant. Not all children received all tests. Age at last visit ranged from 8 months to 16.5 years (median 4 years). Twelve were boys. Fourteen had left hemisphere infarcts. Median age at presentation was 6 months. Eighteen had gestational complications. Fourteen children had at least transient coagulation abnormalities (ACLA = 11, ACLA + APCR = 1, APCR = 2 with FVL + MTHFR = 1); six of these children had family histories suggestive of thrombosis. Cardiac echocardiogram was unremarkable in the 15 tested. Outcomes included persistent hemiparesis in 22; speech, behavior, or learning problems in 12; and persistent seizures in five, with no evidence of further stroke in any patient. The persistence and importance of coagulation abnormalities in this group need further study.

Brain↗
PubMed2000

Imaging correlates of successful endoscopic third ventriculostomy.

OBJECT: The goal of this study was to determine and compare imaging correlates in pediatric patients who underwent successful or failed endoscopic third ventriculostomies (ETVs). To this end, the authors measured ventricular size changes and the presence of cerebrospinal fluid (CSF) flow void in both groups of children following ETV. METHODS: Images obtained in children with hydrocephalus immediately before and at least 30 days after having undergone ETV were reviewed by four independent observers (two blinded and two nonblinded). Each observer independently measured the frontal and occipital horn ratio ([FOR], a reliable and valid measure of ventricular size) and provided a subjective assessment of the presence of a flow void at the ETV site, the degree of periventricular edema, and the amount of CSF over the cerebral hemispheres. There were 29 children whose mean age was 6.6 years at the time of ETV and who had a mean postoperative follow-up period lasting 1.6 years. Postoperatively, the mean reduction in ventricular size (as measured using the FOR) was 7% (95% confidence interval [CI] 3-11%) in cases that were deemed failures (eight patients) and 16% (95% CI 12-20%) in clinically successful cases (21 patients). This reduction was significantly greater in cases of clinical success compared with those that were deemed failures (p = 0.03, t-test). There were no substantial differences between blinded and nonblinded assessments. Flow void was present in 94% of successes and absent in 75% of failures (p = 0.01, Fisher's exact test). The other subjective assessments were not significantly different between the groups of successes and failures. CONCLUSIONS: Ventricular size appears to be somewhat reduced in both groups of patients who underwent clinically successful and failed ETV; however, the reduction is significantly greater among clinically successful cases. The presence of a flow void also appears to correlate with clinical success and its absence with clinical failure.

Adolescent↗
PubMed2000

Selected interventional procedures for pediatric head and neck vascular lesions.

Although vascular malformations are commonly seen in children, they are lesions managed best by an experienced multidisciplinary team. Recognizing, investigating, and diagnosing the type of vascular malformation is critical to determining treatment modality and pathway. Generic identification-despite Mulligan's excellent classification-or confusing vascular malformations with hemangiomas are both inappropriate because treatment is quite different for these separate groups of diseases. Additionally, an understanding of the recognition and classification of vascular malformations is essential for effective family counseling and management of these childhood lesions.

Arteriovenous Malformations↗
PubMed1999

MR characteristics of malignant spinal cord astrocytomas in children.

OBJECTIVE: Malignant spinal cord astrocytomas are rare tumors and their specific MR characteristics have not been previously described. We present a detailed MR analysis of four children with malignant astrocytoma. METHODS: A review of the clinical database at the Hospital for Sick Children, Toronto revealed four patients with histologically-verified malignant spinal cord astrocytomas (WHO Grade 3 or 4) with pre-operative MR available for retrospective review. RESULTS: There were three boys and one girl with a mean age at presentation of four years (range 7 months-12 years). Mean duration of symptoms prior to presentation was six weeks (range 3 days-5 months). Pre-operative MR analysis revealed that all tumors were located in the cervical or cervico-thoracic regions and expanded the cord over an average of 6.5 vertebral levels. The signal was usually hypointense on T1-weighted and hyperintense or mixed intensity on T2-weighted images. In the three cases where gadolinium was given, all demonstrated enhancement (one rim enhancement with a discrete border and two with inhomogeneous central enhancement). One tumor appeared to be exophytic, one had a significant cystic component, and none showed evidence of hemorrhage. Pre-operative leptomeningeal spread of tumor was documented in two of four cases and involved intracranial spread in both cases. CONCLUSIONS: There did not appear to be any specific MR characteristics to help differentiate a malignant astrocytoma from a low-grade tumor, except for the high rate of leptomeningeal spread at presentation. It is recommended that full neuraxis MR imaging be performed pre-operatively in children in whom a rapidly progressive clinical course suggests a malignant lesion. This will likely have a high positive yield and provide valuable information prior to surgical intervention.

Astrocytoma↗
PubMed1999

Straightening of aberrant carotid arteries with age in velocardiofacial syndrome.

Two cases of velocardiofacial syndrome demonstrated spontaneous straightening over a 4-year period of previously deviated carotid arteries on contrast enhanced computed tomography. Based on this finding, uncomplicated traditional pharyngeal flaps were performed on both patients. It is unknown whether straightening of aberrant vessels with age is the rule or the exception in this patient population.

Adolescent↗
PubMed1999

Measurement of ventricular size: reliability of the frontal and occipital horn ratio compared to subjective assessment.

INTRODUCTION: The frontal and occipital horn ration (FOR) has recently been described as a simple, linear measurement of ventricular size that correlates very well with ventricular volume. This study further characterizes the measurement properties of the FOR by investigating its interobserver reliability and comparing it to a subjective assessment of ventricular size. METHODS: Axial images (CT and MR) of children with hydrocephalus taken before and after third ventriculostomy were reviewed by 4 independent observers. Two observers were blinded to patient identity and clinical status and 2 observers were nonblinded. Each observer independently recorded linear measurements from which the FOR was calculated for each image. Each reviewer also made a separate subjective assessment of the degree of hydrocephalus on a 9-point adjectival scale. Reliability was calculated using a repeated-measures analysis of variance (ANOVA) and an intraclass correlation coefficient (ICC) with random image and observer effects. RESULTS: There were 120 separate observations (4 observers, 30 images). The FOR ranged from 0.33 to 0.75 (mean 0.55, standard deviation 0.11). The reliability coefficient was 0.93 (95% confidence interval, CI 0.80-0.97) between the 2 blinded observers and 0.98 (95% CI, 0.95-0.99) between the 2 nonblinded observer. The overall interobserver reliability for all 4 observers was 0.95 (95% CI 0.92-0.98). The mean FOR for each observer was very similar, regardless of the observer's blinding status. However, the reliability of the observers' subjective assessment of the hydrocephalus was much lower (ICC = 0.77, 95% CI 0. 60-0.88). CONCLUSIONS: The FOR demonstrates excellent interobserver reliability (>0.9) and was superior to subjective assessments of hydrocephalus. In this study, excellent reliability was maintained regardless of the blinding status of the observers. This further demonstrates the properties of the FOR as a simple and reproducible measure of ventricular size. It is suitable for use in clinical studies, possibly even in situations in which observer blinding is not possible.

Cerebral Ventricles↗
PubMed1999

Primary cerebellar glioblastomas multiforme in children. Report of four cases.

Primary cerebellar glioblastomas multiforme are exceedingly rare in children. The authors therefore retrospectively characterized the clinical behavior and pathological features of these tumors. A review of the database at the Hospital for Sick Children, Toronto, Canada revealed four patients with cerebellar tumors that displayed significant pleomorphism, hypercellularity, mitoses, and necrosis with pseudopalisading. The authors performed a detailed clinical, radiological, histological, and immunohistochemical analysis of the tumors in these four children (three boys and one girl; average age at presentation 7 years; range 21 months-15 years). Magnetic resonance imaging and computerized tomography most commonly revealed a large lesion with minimal edema, inhomogeneous contrast enhancement, and a discrete border. Tumor resection was subtotal in one patient and gross total in three patients. Immunostaining of the tumor cells with antisera to glial fibrillary acidic protein and vimentin was positive in varying degrees. Initial adjuvant therapy consisted of local radiation only (one patient), chemotherapy only (one patient), and radiation and chemotherapy (one patient). One patient received no adjuvant therapy. Tumor recurrence was documented in all patients: two local recurrences (at 3.5 and 7 months), one spinal recurrence (at 14 months), and one local recurrence with ventricular and spinal spread (at 8 months). Ultimately, three of the four patients developed leptomeningeal tumor spread. Patient follow up ranged from 8 to 17 months (mean 12.5 months). Three patients were dead at last follow up with a mean survival of 15 months. The prognosis for patients with cerebellar glioblastomas is extremely poor, and the tumor has a tendency for cerebrospinal fluid dissemination. The optimal management of patients harboring of these difficult-to-treat tumors, including the role of craniospinal radiation and chemotherapy, has not yet been achieved.

Adolescent↗
PubMed1999

The reliability of the "absent cistern sign" in assessing LP shunt function.

OBJECTIVE: One of the difficulties with lumboperitoneal (LP) shunts has been non-invasively ascertaining shunt function. It has been previously reported that in the presence of a functioning LP shunt the perimesencephalic cisterns become obliterated--the "absent cistern sign". In order to more rigorously test this association we performed a retrospective analysis of LP shunt patients at the Hospital for Sick Children, Toronto. METHODS: The CT scans of all patients undergoing LP shunting over a 17 year period were reviewed. The "absent cistern sign" and ventricular size were compared against the results of either an isotope shunt study or surgical findings performed within 2 days of the CT. RESULTS: There were 38 CT scans (27 patients) performed within 2 days of an isotope shunt study and 15 CT scans (14 patients) performed within 2 days of a surgical intervention. These results give the absent cistern sign a sensitivity of 75% and a specificity of 57% when compared to the shunt isotope findings and a sensitivity of 100% and a specificity of 50% when compared to the surgical findings. Over 30% of the CT scans showed ventriculomegaly in the presence of a functioning shunt and, conversely, nearly 45% of the CT scans had normal or small lateral ventricles in the presence of a malfunctioning shunt. CONCLUSIONS: The "absent cistern sign" appears to reliably rule out a completely blocked shunt, but is less reliable in detecting a normal or partially obstructed shunt. Ventricular size correlates poorly with LP shunt function.

Adolescent↗
PubMed1996

Is pharyngoplasty a risk in velocardiofacial syndrome? An assessment of medially displaced carotid arteries.

The association of medially positioned internal carotid arteries and velocardiofacial (Shprintzen) syndrome was first made in 1987. This is also the most common syndrome associated with facial clefting. The potentially dangerous implications in children with this syndrome requiring pharyngoplasty for velopharyngeal incompetence and stigmatized hypernasal speech involve potential damage to these vessels. This three-part study was undertaken to analyze this anatomic variant. First, a group of 25 children with velocardiofacial syndrome, velopharyngeal incompetence, and obvious posterior pharyngeal pulsations seen on nasendoscopy was studied by CT angiography to determine the degree of this abnormal vascular pattern. This technique, together with three-dimensional reconstructions, made it possible to determine the precise location of these abnormally positioned vessels. Second, our routine superiorly based pharyngeal flap was measured by lateral cervical x-ray to show the distal tip of the flap. The variance was minimal and demonstrated the tip of most flaps to be at the disk between the C2 and C3 vertebrae. By correlating this information with the CT angiography, the risk of surgery can be determined on strict anatomic grounds, allowing customized flap design in some unilateral cases. In this series of children, routine superiorly based pharyngoplasty would be safe in 52 percent, while in 28 percent a pharyngeal flap would be safe if custom designed, and in the remaining 20 percent surgery should not be attempted because the risk of damage to the carotid arteries is too great. Third, in a double-blind study, velocardiofacial children with obvious pulsations seen on nasendoscopy were grouped with other children with palatal dysfunction. When only endoral examination was performed by plastic surgeons and plastic surgical residents, no vascular pulsations were ever seen. This indicates another important role of nasendoscopy in the preoperative assessment of children for palatopharyngoplasty.

Carotid Arteries↗
PubMed1995

Assessment of the effect of head and neck position on upper airway anatomy in sedated paediatric patients using magnetic resonance imaging.

Upper airway patency can be compromised when children (or adults) receive sedative medication. The study examines the effect of two different positioning techniques (use of the 'sniff position pillow' (SPP) and shoulder elevation (SE) on maintenance of upper airway patency using MRI in 21 children sedated with intravenous pentobarbital (5-8 mg.kg-1). Children positioned on the SPP had a significantly greater degree of atlanto-occipital extension (P < 0.05), and a significantly greater nasopharyngeal diameter (P < 0.05) than those with shoulder elevation. The degree of atlanto-occipital extension was not significantly correlated with pharyngeal diameter (R = -0.68). No clinical signs of upper airway obstruction were noted and oxygen desaturation did not occur. Both positioning techniques were consistently associated with upper airway patency under the study conditions described. In obligate nose breathers to whom sedative agents are administered, the SPP is more likely to maintain nasopharyngeal patency than shoulder elevation.

Adjuvants, Anesthesia↗
PubMed1994

Nasal dermoid sinus cysts: an unusual presentation, computed tomographic scan findings, and surgical results.

Midline nasal dermoid cysts are congenital lesions resulting from aberrant embryological development. Accurate diagnosis and effective treatment are essential to avoid craniofacial skeletal deformations, cyst rupture, and infection that could cause cutaneous, ocular, or intracranial complications. We report an unusual case of congenital midline nasal dermoid cysts in which an 18-month-old child presented to a hospital emergency department with periorbital cellulitis. It resulted from multiple midline nasal dermoid cysts involving the nasal, forehead, and both orbital regions but without intracranial extension. The patient was successfully managed with a craniofacial approach.

Bone Transplantation↗
PubMed1994

Frontonasal and craniofrontonasal dysplasia: preoperative quantitative description of the cranio-orbito-zygomatic region based on computed and conventional tomography.

The unoperated crano-orbito-zygomatic complex of 18 children (mean 4.7 years) with frontonasal dysplasia (FND) and 12 children (mean 1.1 years) with crainofrontonasal dysplasia (CFND) was quantified by 15 standard measurements performed on either computed tomography scans or facial tomograms. The results were compared with age-matched control values. In the FND group, the mean anterior interorbital and mid-interorbital distances were significantly increased at 148% and 118% of normal, and in the CFND patients, at 177% and 140% of normal. Excessive medial orbital wall protrusion (mean, 145% of normal in FND and 177% in CFND), shortened zygomatic arch lengths (mean, 94% of normal in FND and 91% in CFND), and reduced cephalic lengths (mean, 96% of normal in FND and 83% in CFND) were all observed. An expanded interzygomatic buttress distance was documented only in the CFND group, at 11% of normal. The clinical presentation of craniofacial deformities such as FND and CFND can be objectively described by a numerical analysis of the bony pathology.

Adolescent↗
PubMed1994

Intracranial nasal dermoid sinus cysts: computed tomographic scan findings and surgical results.

From July 1987 to January 1991, 14 patients, ages 1 to 19 years (mean 6 years), were seen with nasal dermoid sinus cysts, a congenital lesion with the potential for intracranial extension. Each patient was assessed clinically for cyst location, symptoms, associated craniofacial deformity, and other congenital anomalies. In 5 (36 percent) of the 14 patients, ages 4 to 48 months (mean 25 months), computed tomographic scans indicated indirect signs of intracranial extension, which were confirmed intraoperatively and histologically in all 5 patients. After neurosurgical consultation, a combined single-stage intracranial-extracranial approach was used to excise the lesion. No perioperative complications occurred. Clinical assessment (follow-up 20 to 40 months, mean 31 months), confirmed by postoperative CT scan 1 year after surgery, indicated no evidence of recurrence, residual skeletal contour defects, or deformity; forehead and nasal growth were qualitatively normal, and scar appearance was satisfactory. Our experience indicates that intracranial extension of nasal dermoid sinus cysts seen at a tertiary care referral center are not rare, that computed tomography scan permits accurate diagnosis, and that the single-stage intracranial-extracranial approach to resection is effective and results in minimal morbidity.

Adolescent↗
PubMed1993

Tonsillar herniation: the rule rather than the exception after lumboperitoneal shunting in the pediatric population.

Although the development of tonsillar herniation (acquired Chiari malformation) in association with lumboperitoneal (LP) shunting is well recognized, it has previously been considered rare. In order to ascertain the incidence of this complication after LP shunting, the authors undertook a retrospective study of all patients in whom this form of shunt had been inserted between 1974 and 1991 at The Hospital for Sick Children, Toronto. In the 143 patients, the mean age at insertion was 3.3 years and the indications for shunt placement were hydrocephalus (81%), pseudotumor cerebri (7%), cerebrospinal fluid fistula (6%), and posterior fossa pseudomeningocele (6%). The mean follow-up period was 5.7 years, during which time there was one shunt-related death due to unsuspected tonsillar herniation. Five other patients developed symptomatic tonsillar herniation treated by suboccipital decompression. Review of all computerized tomography (CT) scans not degraded by artifact showed evidence of excess soft tissue at the level of the foramen magnum in 38 (70%) of 54 patients so studied. In order to confirm that this CT finding represented hindbrain herniation, sagittal and axial magnetic resonance (MR) images were obtained for 17 asymptomatic patients and revealed tonsillar herniation (range 2 to 21 mm) in 12 (70.6%). In addition, some of these asymptomatic patients had evidence of uncal herniation and mesencephalic distortion. Similarities and distinctions are drawn between the morphological changes occurring after LP shunting and those seen in association with the Chiari I and II malformations. Although less than 5% of this study population required treatment for tonsillar herniation, the incidence of this complication was high in asymptomatic patients; MR imaging surveillance for patients with LP shunts is therefore recommended.

Adolescent↗
PubMed1993

Neuronal heterotopia with capillary penetration of neurons and cortical dysplasia in a patient with complex partial seizures. Case report.

Unusual pathological findings were encountered in a temporal lobectomy specimen from a 9-year-old boy with intractable complex partial seizures. Magnetic resonance imaging revealed an enlarged left temporal lobe, with diffuse high signal intensity over the cortex and poor gray-white differentiation on T2-weighted imaging; single-photon emission computerized tomography showed decreased blood flow. Active epileptiform discharges were identified in the left temporal lobe with focal slow waves and generalized epileptiform paroxysms. Pathologically, the cortex revealed changes of focal cortical dysplasia with extensive disorganization of neuronal morphology, layering, and orientation as well as focal polymicrogyria. The cortical-white matter junction was indistinct with extensive neuronal heterotopias in the white matter. Large pale balloon cells akin to those seen in tuberous sclerosis were found scattered within the cortex and white matter. The most striking finding was that of a heterotopic nodule in the white matter, which revealed abnormal neurons with penetration of cell bodies by capillaries. Ultrastructurally, there were no degenerative changes in these neurons, and this unusual phenomenon is attributed to a developmental disturbance affecting neuronal, glial, and vascular elements.

Brain Neoplasms↗
PubMed1993

Congenital malformations of the spine.

The radiology of the congenital malformations of the spine has undergone significant advancement with the advent of newer modalities including computed tomography and, in particular, magnetic resonance imaging. Correlation with etiology and pathologic findings has improved. Congenital malformations have been classified according to neurulation and disjunction failures (dorsal) and those with persistent neurenteric connections with notochordal splitting (ventral). The most important benefit of the current state of imaging is the accurate morphologic representation of the malformation provided for the surgeon.

Child↗