Derek Armstrong

RELX Group (Netherlands)

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Jeffrey C. Posnick

Georgetown University

Susan Blasér

University of Toronto

Daune MacGregor

Hospital for Sick Children

Gabrielle deVeber

SickKids Foundation

Mubeen F. Rafay

Children's Hospital of Winnipeg

Mahendranath Moharir

Hospital for Sick Children

James M. Drake

University of Toronto

Nomazulu Dlamini

Hospital for Sick Children

Mark D. Wells

Zimmer Biomet (Switzerland)

Judith Garcia‐Aymerich

Pompeu Fabra University

Cooperative Institutions

RELX Group (Netherlands)

Hospital for Sick Children

University of Toronto

SickKids Foundation

University College London

Centro de Investigación Biomédica en Red de Epidemiología y Salud Pública

University of Amsterdam

Instituto de Salud Carlos III

Amsterdam University Medical Centers

Academic Medical Center

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Metopic and Sagittal Synostosis

Plastic & Reconstructive Surgery (1995)

Jeffrey C. Posnick Derek Armstrong Uldis Bite

This study applied a proven method for obtaining intracranial volume measurements using CT scans to (1) measure the intracranial volume of a consecutive series of children with either metopic or sagittal synostosis prior to any craniofacial procedure, (2) perform a standard cranio-orbital operation in each child, follow them longitudinally, and remeasure their intracranial volume 1 year later, and (3) compare their intracranial volumes with those of an age- and gender-matched cohort and review their cranial growth velocity. The study included 18 children who presented sequentially with untreated isolated nonsyndromic sagittal (n = 8) and metopic (n = 10) synostosis between 1987 and 1990 and who subsequently underwent cranio-orbital reconstruction by the senior author (Posnick) in conjunction with a pediatric neurosurgeon. The primary method of osteotomy and bone-graft fixation varied (i.e., wires, miniplates and microplates and screws). The series included 5 females and 13 males with an average age at the time of operation of 27 months (range 6 to 87 months). The postoperative clinical follow-up ranged from 13 to 47 months at the close of the study. Comparison of our patients' preoperative intracranial volumes with age- and gender-matched volumes available through Lichtenberg showed that 16 of 18 (89 percent) had volumes at or greater than the mean, with 44 percent (7 of 16) exceeding 2 standard deviations above the mean. When comparing our patients' late postoperative volumes with the Lichtenberg normative measurements, 94 percent achieved values at or greater than the mean. All patients achieved increased intracranial volume in association with the surgery performed and the time that lapsed between scan intervals. The majority of our patients (16 of 18) followed an intracranial volume growth curve that closely approximated the norm but with a starting point determined by the preoperative value. Two of 18 followed a growth curve that exceeded the rate of expansion expected for normal children. Our findings suggest that premature closure of either the sagittal or metopic suture does not result in diminished intracranial volume prior to or after the cranio-orbital procedures carried out in childhood. For the majority of the children in our study, both the preoperative intracranial volume and the rate of cranial expansion approximated or surpassed that of children without synostosis. The surgical techniques of skull and upper orbital reshaping with varied forms of osteotomy and graft fixation did not result in a global form of growth restriction. These findings are contrary to standard thinking about the biologic effects of craniosynostosis and raise new questions about our rationale for treatment.

10.1097/00006534-199508000-00007

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Citations (92)

Intra-arterial Tissue Plasminogen Activator for Thrombosis Complicating Cerebral Angiography in a 17-Year-Old Girl

Journal of Child Neurology (2003)

Meredith R. Golomb Mubeen F. Rafay Derek Armstrong Patricia Massicotte Rosalind Curtis

Few reports describe the use of intraarterial recombinant tissue plasminogen activator to treat intracranial thrombosis in children. A 17-year-old girl with a history of prior venous thrombosis developed a left middle cerebral artery thrombus during diagnostic cerebral angiogram. Therapy with intra-arterial tissue plasminogen activator was initiated. An immediate follow-up angiogram demonstrated recanalization, and diffusion-weighted magnetic resonance imaging 9 hours later showed no evidence of infarction. Following the angiogram, femoral artery thrombosis developed. Treatment with supratherapeutic levels of heparin, localized delivery of intra-arterial tissue plasminogen activator, embolectomy, danaparoid, and dipyridamole failed to re-establish perfusion to the lower leg, and below the knee amputation was required. Neurologic examination remained normal 1 year later. Cerebral damage was avoided with the use of emergency intra-arterial tissue plasminogen activator for cerebral artery thrombosis in this child.

Magnetic resonance angiography

10.1177/08830738030180060301

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Craniocervical Arterial Dissection in Children: Clinical and Radiographic Presentation and Outcome

Journal of Child Neurology (2006)

Mubeen F. Rafay Derek Armstrong Gabrielle deVeber Trish Domi Anthony K.C. Chan

Craniocervical arterial dissection is a recognized cause of arterial ischemic stroke in children. Whether children with craniocervical arterial dissection have dissection characteristics different from those of adults is unclear. A retrospective review of children, 1 month to 18 years of age, with dissection from two Canadian pediatric ischemic stroke registry centers was conducted. From 213 patients with arterial ischemic stroke, 16 (7.5%) were identified with dissection, 37.5% had warning symptoms, and 50% had a history of head or neck trauma. The clinical presentation included headache (44%), altered consciousness (25%), seizures (12.5%), and focal deficits (87.5%). Dissection involved extracranial vessels in 75% and anterior circulation in 56%. Follow-up included complete recovery in 43%, mild to moderate deficits in 44%, and severe deficits in 13%. Fourteen (87.5%) children received antithrombotic treatment. Follow-up angiography showed resolution of abnormalities in 60% of vessels. Total occlusion had the worst outcome for recanalization. In conclusion, the etiology of arterial dissection in the majority of children appears to be either trauma or idiopathic. Long-term angiography shows variable outcomes, depending on the initial findings. The relationship of angiographic outcomes with recurrent strokes requires further study in pediatric dissection. ( J Child Neurol 2006;21:8—16).

Arterial dissection

Pediatric Stroke

Etiology

Stroke

Vertebral artery dissection

Presentation (obstetrics)

10.1177/08830738060210010101

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Citations (152)

Metopic Synostosis

Plastic & Reconstructive Surgery (1994)

Jeffrey C. Posnick Kant Y. Lin Phillip Chen Derek Armstrong

Our study applied a method of using 14 clinically relevant measurements of CT scan images to document skeletal dysmorphology in patients with metopic synostosis to determine the effectiveness of their surgical procedure after a minimum of 1 year. Ten consecutive patients with metopic synostosis who underwent a standard surgical procedure were reviewed. Preoperative and postoperative (>1 year) CT scans were compared with those of age-matched controls. Percentages of normal were then compared for significant differences. Preoperative cranial vault measurements revealed a narrowed anterior inter-coronal distance at 92 percent of normal. Orbital measurements showed a narrowed anteromedial wall interorbital distance at 79 percent of normal, a narrowed lateral orbital wall distance at 94 percent, and an elevated medial orbital wall protrusion beyond the plane of the lateral orbital walls at 115 percent. After surgery, the intercoronal distance was significantly corrected to 101 percent, the anteromedial wall interorbital distance was improved but remained undercorrected at 90 percent, and the medial wall protrusion was significantly decreased to 98 percent of normal. Quantitative measurements of CT scan images confirmed clinically observed physical findings in unoperated trigonocephaly to be orbital hypotelorism, retruded lateral orbital rims, and a narrowed bitemporal width. The surgical technique corrected the lateral orbital wall aspects of the deformity as well as the narrowed anterior cranial vault width and improved the orbital hypotelorism. (Plast. Reconstr. Surg. 93: 16, 1994.)

Trigonocephaly

Cranial vault

10.1097/00006534-199401000-00003

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Citations (101)

Late Complications of Vertebral Artery Dissection in Children: Pseudoaneurysm, Thrombosis, and Recurrent Stroke

Journal of Child Neurology (2009)

Marilyn A. Tan Derek Armstrong Daune MacGregor Adam Kirton

Craniocervical arterial dissection is an important cause of childhood arterial ischemic stroke, accounting for 7.5% to 20% of cases. Significant neurologic morbidity and mortality may result and recurrence risk may be higher than in adults. However, the natural history and long-term outcome of pediatric dissection are poorly studied. We report 3 cases of extracranial vertebral artery dissection with complications including pseudoaneurysm formation, recurrent stroke, and late spontaneous thrombosis of the dissected artery. These cases illustrate the dynamic processes involved in vascular injury and healing of vertebral artery dissection in children over years, with potential implications for long-term management and prevention of recurrence.

Pseudoaneurysm

Vertebral artery dissection

Arterial dissection

Stroke

10.1177/0883073808324775

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Citations (40)

Predicting postresection hydrocephalus in pediatric patients with posterior fossa tumors

Journal of Neurosurgery Pediatrics (2009)

Jay Riva-Cambrin Allan S. Detsky Maria Lamberti-Pasculli Michael A. Sargent Derek Armstrong

Object Approximately 30% of children with posterior fossa tumors exhibit hydrocephalus after tumor resection. Recent literature has suggested that prophylactic endoscopic third ventriculostomy diminishes the risk of this event. Because the majority of patients will not have postoperative hydrocephalus, a preoperative clinical prediction rule that identifies patients at high or low risk for postresection hydrocephalus would be helpful to optimize the care of these children. Methods The authors evaluated a derivation cohort of 343 consecutive children with posterior fossa tumors who underwent treatment between 1989 and 2003. Multivariate methods were used on these data to generate the Canadian Preoperative Prediction Rule for Hydrocephalus. The rule's estimated risk of postresection hydrocephalus was compared with risk observed in 111 independent patients in the validation cohort. Results Variables identified as significant in predicting postresection hydrocephalus were age < 2 years (score of 3), papilledema (score of 1), moderate to severe hydrocephalus (score of 2), cerebral metastases (score of 3), and specific estimated tumor pathologies (score of 1). Patients with scores ≥ 5 were deemed as high risk. Predicted probabilities for the high- and low-risk groups were 0.73 and 0.25, respectively, from the derivation cohort, and 0.59 and 0.14 after prevalence adjustment compared with the observed values of 0.42 and 0.17 in the validation cohort. Conclusions A patient's score on the Preoperative Prediction Rule for Hydrocephalus will allow improved patient counseling and surgical planning by identifying patients at high risk of developing postresection hydrocephalus. These patients might selectively be exposed to the risks of preresection CSF diversion to improve outcome.

Endoscopic third ventriculostomy

Ventriculostomy

10.3171/2009.1.peds08298

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Citations (136)

Childhood Fibrous Dysplasia Presenting as Blindness: A Skull Base Approach for Resection and Immediate Reconstruction

Pediatric Neurosurgery (1993)

Jeffrey C. Posnick Mark D. Wells James M. Drake Raymond Buncic Derek Armstrong

Fibrous dysplasia is an abnormal fibroosseous process of bone of unknown cause. The Incidence of skull involvement varies, painless enlargement being the most common presenting symptom. Change in vision is a rare but recognized finding. We report a 3-year-old boy with extreme fibrous dysplasia involving the skull base, who presented with blindness. He underwent exposure osteotomies of the frontal bones and orbits to provide access for skull base tumor removal. The orbital roofs were reconstructed with microplate-fixed cranial grafts. One and one half years after tumor excision followed by immediate reconstruction, the boy retains facial symmetry, and his ocular function has not deteriorated.

Orbit (dynamics)

10.1159/000120742

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Citations (26)

Monobloc and Facial Bipartition Osteotomies for Reconstruction of Craniofacial Malformations: A Study of Extradural Dead Space and Morbidity

Plastic & Reconstructive Surgery (1996)

Jeffrey C. Posnick Mohammed M. AI-Qattan Derek Armstrong

This study evaluated the presence of extradural dead space following a monobloc or facial bipartition osteotomy and examined its natural history and relationship to postoperative infection and the presence of a ventriculoperitoneal shunt at the time of osteotomy in a consecutive series of patients with craniofacial dysostosis, frontonasal dysplasia, midline cranio-orbital clefts, and orbital hypertelorism. Only patients followed for at least 1 year were included in the study (range 1.3 to 5.5 years). The 23 patients studied were divided into three groups: 10 patients (mean age 9 years) underwent a monobloc osteotomy with advancement, 7 (mean age 8 years) a facial bipartition osteotomy with advancement, and 6 (mean age 7 years) a facial bipartition osteotomy without advancement. Standard craniofacial computed tomographic (CT) scans were obtained for each patient early after surgery (within 2 weeks in 13 patients and at 6 to 8 weeks in 10 patients) and again 1 year after surgery in every case. The extradural dead space was measured from a reproducible axial CT scan slice for each patient at each postoperative interval. An initial dead space was documented in the retrofrontal region of the anterior cranial fossa when the reconstruction incorporated forward projection of the osteotomy parts. This space was found to be obliterated by the expanded brain by 6 to 8 weeks in the patients examined by CT scan at this interval (n = 10) and by 1 year in all patients. Perioperative complications also were documented. The presence of a ventriculoperitoneal shunt at the time of osteotomy (7 of 23 patients) did not increase the risk of complications or alter the pattern of dead space closure after operation. Two patients developed infectious complications that were managed without long-term consequences. (Plast. Reconstr. Surg. 97: 1118, 1996.)

Craniofacial surgery

10.1097/00006534-199605000-00005

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Citations (51)

Neurofibromatosis Bright Objects in Children With Neurofibromatosis Type 1: A Proliferative Potential?

PEDIATRICS (1999)

Paul D. Griffiths PhD FRCR Susan Blasér William Mukonoweshuro Derek Armstrong

Objectives. The purpose of this study was to investigate the natural history of the high signal intensities shown on long TR sequences—neurofibromatosis type 1 bright objects (NBO)—in children with neurofibromatosis type 1 (NF1). We have paid particular attention to the development of tumors in these areas of abnormality. Methods. During a 12-month period in 1992 to 1993, 46 children with clinically proven NF1 had a magnetic resonance (MR) examination at our institution. These were reviewed along with any previous or subsequent MR examinations that had been performed. We recorded the number, volume, and distribution of the abnormal high signal intensities and their change with time when serial examinations were performed. Results. NBO were found in 93% of 46 children with NF1 on the original cross-sectional study. The most common anatomic sites were the globus pallidus (30.4%), cerebellum (23.5%), and midbrain (16.2%). The number and volume of NBO varied significantly with age. NBO were uncommon in children younger than 4 years but were very common and extensive between 4 to 10 years. A significant reduction in the number and volume of NBO was demonstrated in children older than 10 years as shown on both the cross-sectional and longitudinal portions of the study. Eight brain tumors (nonoptic pathway) were demonstrated in the 46 children (17%) with 1 child having two tumors. Only 1 child had symptoms referable to the tumor at the time of diagnosis. Five tumors developed in NBO that were documented on serial MR examinations. All those cases developed in children aged 7 to 12 years, and all these children had higher than average numbers and volumes of NBO. Conclusions. NBO occur commonly in children with NF1 and are most prevalent between the ages of 4 and 10. We have shown a high frequency of brain tumors in our children with NF1, but the majority of these were asymptomatic. We have demonstrated proliferative change NBO in 11% of 46 children. Most NBO regress with age and seem to be benign, however, young children with a large number and volume of NBO should be followed closely with regular MR examinations because of an increased risk of proliferative change. neurofibromatosis type 1, magnetic resonance, tumor, astrocytoma, childhood.

Natural bond orbital

Abnormality

10.1542/peds.104.4.e49

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Citations (85)

Choroid plexus size in young children with Sturge-Weber syndrome.

American Journal of Neuroradiology (1996)

Paul Griffiths Susan Blasér M B Boodram Derek Armstrong Derek C. Harwood-Nash

PURPOSE To assess the size of the choroid plexus in young children with unilateral and bilateral Sturge-Weber syndrome. METHODS Subjects included 15 children 4 years old or younger with Sturge-Weber syndrome. Eleven cases were unilateral and four were bilateral. Unilateral or bilateral involvement was determined by the distribution of abnormal leptomeningeal enhancement on MR images. The diameters of the choroid plexus were measured on contrast-enhanced axial MR images. The choroid plexus of the affected and unaffected sides in these cases were compared with those of 15 age-matched children without Sturge-Weber syndrome who were being examined for seizures. RESULTS Our results show a wide variation in the size of the choroid plexus in children with Sturge-Weber syndrome; however, plexus associated with a hemisphere affected by Sturge-Weber syndrome were significantly larger than those on the unaffected side and in the age-matched control group. The size of the choroid plexus was positively correlated with the extent of leptomeningeal involvement as demonstrated by abnormal contrast enhancement. CONCLUSION The choroid plexus is enlarged early in the course of Sturge-Weber syndrome in both unilateral and bilateral cases. There is a positive correlation between choroid plexus size and extent of leptomeningeal involvement in children with Sturge-Weber syndrome.

Sturge–Weber syndrome

Choroid

Choroid plexus papilloma

Plexus

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Citations (45)