Biomedical subjects

Daniel J Licht

Publications and source records attributed to Daniel J Licht.

9 recordsLinked to original sources

PubMed2006

Pediatric perfusion MR imaging using arterial spin labeling.

Cerebral blood flow (CBF, cerebral perfusion) mirrors cerebral metabolic demand and neuronal function, and therefore, is a vital parameter in the evaluation of pediatric brain injury and recovery. Until recently, measurement of CBF involved intravenous bolus injection of contrast agents or nuclear medicine methods that were technically difficult or ethically problematic in pediatrics. The development of arterial spin label (ASL) perfusion MR imaging as a noninvasive method for measuring CBF allows for the increased ability to measure this vital physiologic parameter in any age group. This article presents the technical aspects of performing ASL perfusion MR imaging in pediatrics, and discusses its current use in clinical studies and its potential for influencing important management strategies in specific disease entities.

Anemia, Sickle Cell↗

PubMed2006

Mimics of childhood stroke: characteristics of a prospective cohort.

BACKGROUND: Little is known about the clinical features and spectrum of diagnoses in children with "stroke mimics," those with acute neurologic deficits but without cerebrovascular diseases. OBJECTIVES: Our goal was to describe patients with stroke mimics and to determine if clinical features predict benign diagnoses. METHODS: Our stroke consult team registered a prospective consecutive cohort of 143 patients with acute presentations suspicious for cerebrovascular disease from November 2003 to November 2004. Cases in which stroke was ruled out (stroke mimics) were reviewed for clinical features and diagnostic test results and were classified "benign" if there was no structural brain lesion and there was an expectation of complete recovery. RESULTS: Of the 143 cases evaluated for suspected stroke, 30 (21%) had stroke mimics. Presenting signs included seizure (n = 11), headache (n = 9), mental status change (n = 6), focal weakness (n = 14), and focal sensory change (n = 7). Eleven patients had "benign" diagnoses (3 migraine, 3 psychogenic diagnoses, 3 musculoskeletal abnormalities, 1 delirium, and 1 episodic vital sign changes). Nineteen patients had "not-benign" diagnoses (3 reversible posterior leukoencephalopathy syndrome, 3 neonatal seizures, 2 vascular anomalies, 2 inflammatory disease, 2 intracranial infection, 2 epilepsy, 2 metabolic stroke, 1 tumor, 1 drug toxicity, and 1 idiopathic intracranial hypertension). Except for the presence of seizures, there were no significant differences in presentation or risk factors between benign and not-benign cases. CONCLUSIONS: Many disorders mimic childhood stroke. History and clinical presentation often do not distinguish the one third of patients with benign disorders from the two thirds with more serious problems, necessitating timely comprehensive investigations, especially brain MRI.

Adolescent↗

PubMed2005

Why perfusion in neonates with congenital heart defects is negative--technical issues related to pulsed arterial spin labeling.

Pulsed arterial spin labeling (PASL) perfusion MRI has unique advantages for measuring cerebral blood flow (CBF) in the pediatric population. In neonates with congenital heart defects (CHDs), however, a considerable number of negative CBF values were observed in PASL perfusion images. A set of specific physiological and biophysical conditions were proposed as plausible explanations for this phenomenon, including small body size, low blood flow, prolonged tracer life time (blood T1) and the "shunt" between pulmonary and systemic circulations in CHD. An optimized PASL scheme with a restricted label volume was proposed, and experimental data demonstrated reduced spurious negative values and lower intersubject variability of perfusion measurements in neonates with CHD as compared to standard PASL sequences.

Adult↗

PubMed2005

Neurological and neuromuscular disease as a risk factor for respiratory failure in children hospitalized with influenza infection.

CONTEXT: The Advisory Committee on Immunization Practices (ACIP) recommends annual influenza vaccination for children with certain chronic medical conditions to prevent serious complications of influenza infection. Little is known about the relative contribution of each of these chronic medical conditions to the development of serious influenza-associated complications. OBJECTIVE: To identify chronic medical conditions that are associated with respiratory failure in children hospitalized with community-acquired laboratory-confirmed influenza. DESIGN, SETTING, AND PATIENTS: A retrospective cohort study of patients aged 21 years or younger hospitalized at The Children's Hospital of Philadelphia with community-acquired laboratory-confirmed influenza during 4 consecutive influenza seasons (June 2000 through May 2004). We examined 9 ACIP-designated high-risk chronic medical conditions and 3 additional chronic medical conditions (neurological and neuromuscular disease [NNMD], gastroesophageal reflux disease [GERD], and history of prematurity) that in recent studies have been associated with influenza hospitalization and severe influenza-related complications. MAIN OUTCOME MEASURES: Rate and odds ratio (OR) of respiratory failure, defined as need for mechanical ventilation. RESULTS: Of 745 children hospitalized with community-acquired laboratory-confirmed influenza, 322 (43%) had 1 or more ACIP-designated high-risk chronic medical conditions. Neurological and neuromuscular disease, GERD, and history of prematurity were present in 12%, 14%, and 3%, of children, respectively. Thirty-two children (4.3%) developed respiratory failure. In multivariate logistic regression analyses, conditions associated with respiratory failure included NNMD (OR, 6.0; 95% confidence interval [CI], 2.7-13.5), chronic pulmonary disease other than asthma (OR, 4.8; 95% CI, 1.5-15.1), and cardiac disease (OR, 4.0; 95% CI, 1.6-10.2). The predicted probabilities of respiratory failure derived from the multivariate model were 12% (95% CI, 7%-20%), 9% (95% CI, 3%-23%), and 8% (95% CI, 4%-18%) for children with NNMD, chronic pulmonary disease, and cardiac disease, respectively. CONCLUSIONS: These results support the ACIP's recent decision to add NNMD to the list of conditions for which annual influenza vaccine is recommended in children. Neurologists and primary care pediatricians should be alerted to the increased risk of respiratory failure and the importance of influenza vaccination in children with NNMD.

Adolescent↗

PubMed2005

Pediatric central nervous system infections and inflammatory white matter disease.

This article reviews the immunology of the central nervous system and the clinical presentation, diagnosis, and treatment of children with viral or parainfectious encephalitis. The emphasis is on the early recognition of treatable causes of viral encephalitis (herpes simplex virus), and the diagnosis and treatment of acute disseminated encephalomyelitis are described in detail. Laboratory and imaging findings in the two conditions also are described.

Central Nervous System↗

PubMed2005

Pediatric palliative, end-of-life, and bereavement care.

The pediatric hospitalist plays an integral role in providing palliative, end-of-life, and bereavement care for children and families. This article focuses on a multifaceted approach to this domain of care in which the physician is a key member of an interdisciplinary team. We believe that we can improve quality of life and relieve suffering only by paying attention to the medical, emotional, spiritual, and practical needs and goals of dying children and their loved ones.

Attitude to Death↗

PubMed2004

Preoperative cerebral blood flow is diminished in neonates with severe congenital heart defects.

OBJECTIVE: Impaired neurodevelopmental outcome represents a major morbidity for survivors of infant heart surgery for congenital heart defects. Previous studies in these neonates have reported preoperative microcephaly, periventricular leukomalacia, and other findings. The hypothesis of this study is that preoperative cerebral blood flow is substantially diminished and might relate to preoperative neurologic conditions. METHODS: Preoperative brain magnetic resonance imaging was performed. Cerebral blood flow measurements in infants with congenital heart defects were obtained by using a novel noninvasive magnetic resonance imaging technique, pulsed arterial spin-label perfusion magnetic resonance imaging. Cerebral blood flow was measured before the operation under standard ventilation and repeated after increased carbon dioxide. RESULTS: A total of 25 term infants were studied. The average age at the time of the operation was 4.4 +/- 4.6 days. Congenital heart defects varied widely. Microcephaly occurred in 24% (6/25). Baseline cerebral blood flow was 19.7 +/- 9.2 mL . 100 g -1 . min -1 (8.0-42.2 mL . 100 g -1 . min -1 ). Five patients had cerebral blood flow measurements of less than 10 mL . 100 g -1 . min -1 . Mean hypercarbic cerebral blood flow increased to 40.1 +/- 20.3 mL . 100 g -1 . min -1 (11.4-94.0 mL . 100 g -1 . min -1 , P < .001). Pairwise analyses found that low hemoglobin levels were associated with higher baseline cerebral blood flow values ( P = .04). Periventricular leukomalacia occurred in 28% (7/25) and was associated with decreased baseline cerebral blood flow values ( P = .05) and a smaller change in cerebral blood flow with hypercarbia ( P = .003). CONCLUSIONS: Structural brain abnormalities are common in these neonates before surgical intervention. Preoperative cerebral blood flow for this cohort was low and drastically reduced in some patients. Low cerebral blood flow values were associated with periventricular leukomalacia. Carbon dioxide reactivity was preserved but might be compromised by some aspects of the cardiac anatomy. The full spectrum of cerebral blood flow measurements with this technique in congenital heart defects and their long-term significance require continued investigation.

Brain↗

PubMed2003

Pediatric perfusion imaging using pulsed arterial spin labeling.

PURPOSE: To test the feasibility of pediatric perfusion imaging using a pulsed arterial spin labeling (ASL) technique at 1.5 T. MATERIALS AND METHODS: ASL perfusion imaging was carried out on seven neurologically normal children and five healthy adults. The signal-to-noise ratio (SNR) of the perfusion images along with T1, M(0), arterial transit time, and the temporal fluctuation of the ASL image series were measured and compared between the two age groups. In addition, ASL perfusion magnetic resonance (MR) was performed on three children with neurologic disorder. RESULTS: In the cohort of neurologically normal children, a 70% increase in the SNR of the ASL perfusion images and a 30% increase in the absolute cerebral blood flow compared to the adult data were observed. The measures of ASL SNR, T1, and M(0) were found to decrease linearly with age. Transit time and temporal fluctuation of the ASL perfusion image series were not significantly different between the two age groups. The feasibility of ASL in the diagnosis of pediatric neurologic disease was also illustrated. CONCLUSION: ASL is a promising tool for pediatric perfusion imaging given the unique and reciprocal benefits in terms of safety and image quality.

Adult↗

PubMed2002

Juvenile dentatorubral-pallidoluysian atrophy: new clinical features.

Dentatorubral-pallidoluysian atrophy is a rare autosomal-dominant neurodegenerative disorder caused by an expansion of a CAG repeat in the atrophin-1 gene on chromosome 12. Dentatorubral-pallidoluysian atrophy is characterized clinically by prominent anticipation and a wide variety of symptoms that depend on age of onset and number of trinucleotide repeats. The juvenile type of dentatorubral-pallidoluysian atrophy, like Huntington's disease, is most commonly inherited via paternal transmission of the gene and most frequently presents with early-onset progressive myoclonus epilepsy with mental retardation and ataxia. We present six affected individuals with dentatorubral-pallidoluysian atrophy from a black family living in North America. This pedigree includes two severe juvenile-onset cases, one of maternal transmission and the other of paternal transmission. Both cases of juvenile-onset disease presented with autistic features and seizures. Interestingly, cranial magnetic resonance imaging performed on the more affected child revealed only mild cerebellar atrophy. The present family expands the clinical description of juvenile-onset dentatorubral-pallidoluysian atrophy and emphasizes the importance of considering dentatorubral-pallidoluysian atrophy in children with progressive myoclonus epilepsy.

Adolescent↗