Pediatrician, Neurologist (brain, nervous system)
33 years of experience

Paradise Valley
7710 N Hummingbird Ln
Paradise Valley, AZ 85253
602-418-6602
Locations and availability (1)

Education ?

Medical School Score Rankings
University of Colorado (1977)
  • Currently 4 of 4 apples
Top 25%

Awards & Distinctions ?

Associations
American Board of Pediatrics
American Board of Psychiatry and Neurology

Publications & Research

Dr. Tarby has contributed to 21 publications.
Title Agenesis of the Corpus Callosum is Associated with Feeding Difficulties.
Date October 2004
Journal Journal of Child Neurology
Excerpt

Our objective was to characterize the common occurrence of feeding and swallowing disorders noticed by our speech therapy department among patients with agenesis of the corpus callosum. All patients with suspected or presumed agenesis of the corpus callosum undergoing therapy for feeding and/or swallowing disorders, including oral and/or pharyngeal dysphagia and oral-sensory disorder, were identified. Their brain magnetic resonance imaging (MRI) studies and charts were reviewed in detail. Seven patients with striking oral-motor and oral-sensory disorder met the criteria for agenesis of the corpus callosum. Particular difficulties noted include oral-sensory defensiveness in five of these seven patients, oral dysphagia/weakness in all seven patients, and pharyngeal dysphagia with risk of aspiration in three of these seven patients. The oral-motor weakness observed in all of the patients affected the strength and coordination necessary for functional oral-phase swallowing. We conclude that feeding and swallowing disorders are significant in children with agenesis of the corpus callosum. Although the pathophysiologic mechanism is not known, recognition of this phenomenon is important because early detection and intervention can facilitate functional feeding and swallowing patterns earlier in these patients, therefore avoiding the adverse and more severe disorders that can arise when dysphagias and/or oral-sensory disorder persist over extended periods of time.

Title Athabascan Brainstem Dysgenesis Syndrome.
Date February 2004
Journal American Journal of Medical Genetics. Part A
Excerpt

We report a new disorder with diverse neurological problems resulting from abnormal brainstem function. Consistent features of this disorder, which we propose should be called the Atabascan brainstem dysgenesis syndrome, include horizontal gaze palsy, sensorineural deafness, central hypoventilation, and developmental delay. Other features seen in some patients include swallowing dysfunction, vocal cord paralysis, facial paresis, seizures, and cardiac outflow tract anomalies. All affected children described are of Athabascan Indian heritage, with eight children from the Navajo tribe and two patients who are of Apache background. The disorder can be distinguished from the Moebius syndrome by the pattern of central nervous system findings, especially the sensorineural deafness, horizontal gaze palsy, and central hypoventilation. Recognition of children with some features of Athabascan brainstem dysgenesis syndrome should prompt investigation for other related abnormalities. Published 2003 Wiley-Liss, Inc.

Title Cerebellar Infarction: an Unrecognized Complication of Very Low Birthweight.
Date January 2003
Journal Journal of Child Neurology
Excerpt

We evaluated 13 children with cerebral palsy who had birthweights under 1085 g. A magnetic resonance image (MRI) of the head was obtained, the findings were compared, and the neonatal records were reviewed. The individual children were classified as to the type of cerebral palsy. On MRI, all had severe injury to the inferior cerebellar hemispheres, mostly symmetric, and in some there was injury to the inferior vermis. The average birthweight was 668 g, and the gestational ages were 24 to 27 weeks. No other outstanding prenatal or postnatal problems were identified. The children had different types of severe cerebral palsy, with only 3 being able to walk. Almost all were mentally retarded and microcephalic. All had visual problems. This report defines a previously underappreciated injury to the cerebellum in extremely premature infants. Further clinical, laboratory, and pathologic studies are needed to better define the underlying mechanisms.

Title Erb's Palsy Contrasted with Klumpke's and Total Palsy: Different Mechanisms Are Involved.
Date July 2002
Journal American Journal of Obstetrics and Gynecology
Excerpt

OBJECTIVE: The purpose of this study was to examine the available evidence regarding the nature of the forces that were involved in the production of a lower plexus palsy or a total (whole arm) palsy, as contrasted with the nature of the forces that resulted in an upper plexus palsy. STUDY DESIGN: This was a review of studies that dealt with specific mechanisms that were supplemented by reports of total palsy that were gleaned from the literature and case reports from the clinical and medical legal cases of the authors. RESULTS: Studies of the forces involved in brachial plexus injury in adults and from cadaver studies in infants who were stillborn or who died in the newborn period attest to the nature of the forces needed to damage the lower plexus. This evidence is reinforced by the case reports. CONCLUSION: Forces other than simple widening of the head-shoulder angle are necessary to disrupt the roots or cords of the lower brachial plexus. The position of the arm and direction of the forces that are applied determine the nature of the lesion.

Title Disuse Osteoporosis As Evidence of Brachial Plexus Palsy Due to Intrauterine Fetal Maladaptation.
Date August 2001
Journal American Journal of Obstetrics and Gynecology
Excerpt

We report what may be overlooked evidence of the effects of intrauterine maladaptation as a cause of brachial plexus palsy. A case of total brachial plexus palsy in the posterior arm associated with Horner's syndrome and severe demineralization of the bones of the affected arm is analyzed. In this litigated case, a report of marked demineralization of the bones of the affected arm was analyzed by the plaintiff's radiology expert as diagnostic of disuse osteoporosis. The presence of clear-cut evidence of disuse osteoporosis during the early neonatal period is compelling evidence of an intrauterine onset of brachial plexus palsy.

Title Fumaric Aciduria: Clinical and Imaging Features.
Date May 2000
Journal Annals of Neurology
Excerpt

Fumaric aciduria (fumaric acidemia, fumarase deficiency) is a rare inborn error of metabolism caused by deficient activity of fumarate hydratase, one of the constituent enzymes of the Krebs tricarboxylic acid cycle. We describe the clinical and imaging features of this disease arising from a consanguineous pedigree in 8 patients in the southwestern United States. Thirteen patients have been previously described in the medical literature. Our patients presented with an early infantile encephalopathy with profound developmental retardation and hypotonia, and most experienced seizures. Previously unreported characteristics described here include structural brain malformations, dysmorphic facial features, and neonatal polycythemia. Magnetic resonance imaging showed multiple abnormalities, including diffuse polymicrogyria, decreased cerebral white matter, large ventricles, and open opercula. Fumaric aciduria should be included in the differential diagnosis of inborn errors of metabolism that cause cerebral malformations and dysmorphic features. The possibility that inborn errors of energy metabolism may cause structural malformations deserves increased recognition.

Title Brachial Plexus Palsy: an Old Problem Revisited Again. Ii. Cases in Point.
Date August 1997
Journal American Journal of Obstetrics and Gynecology
Excerpt

OBJECTIVES: In spite of mounting evidence to the contrary, plaintiffs' expert witnesses continue to maintain that brachial plexus impairment is almost always the result of excessive lateral traction on the head during the last phase of delivery. Case studies are presented to challenge this concept. STUDY DESIGN: Examples encountered in medicolegal consultations were analyzed with this purpose as our focus. RESULTS: Cases of brachial plexus impairment were encountered in which there was no evidence of shoulder dystocia or extreme lateral traction on the fetal head. In one in which shoulder dystocia was recorded, there was also incontrovertible evidence of intrauterine maladaptation. In another, the posterior shoulder was involved. CONCLUSION: To propose that shoulder dystocia with extreme lateral traction on the fetal head after its delivery is not a factor in some cases of brachial plexus impairment would be insupportable. Conversely, to maintain a posteriori that brachial plexus impairment in itself is evidence that such pressure must have been used is untenable.

Title Brachial Plexus Palsy: an Old Problem Revisited.
Date July 1992
Journal American Journal of Obstetrics and Gynecology
Excerpt

OBJECTIVES: It is an almost assumption in obstetric literature that brachial palsy is due to extreme lateral traction on the fetal head during the last phase of delivery. In contrast, there have been reports in the neurologic literature of probable intrauterine origin of brachial plexus palsy. Data to dispute or support the latter view were sought. STUDY DESIGN: With this overview in mind, our perinatal data base was searched for all instances of shoulder dystocia and independently for all diagnoses of brachial plexus impairment. RESULTS: Seventeen instances of brachial plexus impairment associated with shoulder dystocia were found. Twenty-two instances of brachial plexus impairment without mention of shoulder dystocia were ascertained. The characteristics of the two groups were remarkably different, especially in birth weight and in maternal age and parity. CONCLUSIONS: The data are strongly suggestive that intrauterine maladaptation may play a role in brachial plexus impairment. Brachial plexus impairment should not be taken as prima facie evidence of birth process injury.

Title Prenatal Diagnosis of Intracerebellar Hemorrhage: Case Report.
Date August 1990
Journal American Journal of Obstetrics and Gynecology
Excerpt

Evidence continues to accumulate that neurologic damage can occur during the antenatal period, unrelated to intrapartum events. We report a case in which intracerebellar hemorrhage was diagnosed by antepartum ultrasonographic examination. Correlation of fetal heart rate patterns, Apgar scores with neonatal course, and neuropathologic findings are presented. Medicolegal implications are discussed.

Title Local Cerebral Blood Flow As Assessed by Xenon Stable Computed Tomography in Child Drowning.
Date August 1988
Journal Pediatric Radiology
Excerpt

A comatose patient who nearly drowned was studied with xenon stable computed tomography (CT) to assess regional cerebral blood flow (rCBF) after a basic CT studied revealed bilateral lucencies in the basal ganglia. Xenon stable CT revealed increased rCBF in the lucent areas of the basal ganglia and previously unsuspected absence of flow in the posterior circulation. Xenon stable CT may be a more sensitive indicator of ischemic cerebral damage than basic CT.

Title Serial Lumbar Punctures for at Least Temporary Amelioration of Neonatal Posthemorrhagic Hydrocephalus.
Date May 1985
Journal Pediatrics
Excerpt

Serial lumbar punctures for the management of neonatal posthemorrhagic hydrocephalus without intracranial hypertension were evaluated in 16 infants. Cranial ultrasonography to evaluate ventricular size and the Ladd monitor at the anterior fontanel to measure intracranial pressure were utilized immediately before and after lumbar puncture. In 12 patients, a decrease in ventricular size and in anterior fontanel pressure could be effected with each lumbar puncture. In these infants, cessation of progression of the hydrocephalus and intermittent decreases in ventricular size were accomplished. In four patients, lumbar punctures were not successful in decreasing ventricular size or lowering intracranial pressure. Two criteria could be defined to determine whether lumbar puncture could provide at least temporary benefit for the treatment of posthemorrhagic hydrocephalus. The first of these is to establish the presence of communication between lateral ventricles and lumbar subarachnoid space by effecting a decrease in ventricular size and a decrease in intracranial pressure by removal of CSF. The second criterion is to ascertain a critical volume of CSF (usually relatively large) that must be removed in order to effect the above changes. Cranial ultrasonography and measurement of intracranial pressure by application of the Ladd monitor to the anterior fontanel are extremely valuable in the evaluation of lumbar punctures in the management of posthemorrhagic hydrocephalus.

Title Rapidly Progressive Posthemorrhagic Hydrocephalus. Treatment with External Ventricular Drainage.
Date July 1984
Journal American Journal of Diseases of Children (1960)
Excerpt

Nineteen premature infants with progressive posthemorrhagic hydrocephalus with increased intracranial pressure were treated with external ventricular drainage. Progression of hydrocephalus was arrested during the drainage period in each patient. Three of the 19 infants required no further therapy. Sixteen had recurrence of progressive ventricular dilatation, and all but one eventually had placement of a ventriculoperitoneal shunt, although under more favorable medical conditions than existed at the time of institution of external ventricular drainage. Three of the 19 infants died of causes unrelated to the external ventricular drainage. Of the 16 survivors, seven infants had a developmental quotient or formal IQ of over 75. Outcome was poorest for those infants with accompanying intracerebral hemorrhage. We consider ventriculostomy to be an effective temporizing measure in small infants with rapidly progressive posthemorrhagic hydrocephalus with increased intracranial pressure in whom ventricular decompression is necessary and placement of a ventriculoperitoneal shunt is not feasible.

Title Intraventricular Hemorrhage in the Premature Infant.
Date December 1982
Journal Pediatric Clinics of North America
Excerpt

Periventricular-intraventricular hemorrhage is the most important adverse neurologic event of the newborn period. It is very common and can be very severe. Such hemorrhage begins in the germinal matrix but may spread into and throughout the ventricular system. It may be accompanied by hemorrhage within the brin parenchyma. The pathogenesis of periventricular-intraventricular hemorrhage is still imperfectly understood, but relates to the anatomy and physiology of the developing cerebral vasculature and to the biophysical and biochemical environment in which that development proceeds. Periventricular-intraventricular hemorrhage may be marked by a catastrophic clinical deterioration, but is more commonly accompanied by a saltatory progression that may be difficult to detect clinically. Both concomitant neonatal disease and therapeutic intervention for such disease have been implicated in the initiation and exacerbation of periventricular-intraventricular hemorrhage. Real-time ultrasound scanning with portable instruments is now the best procedure for identifying this lesion and for assessing its sequelae. Prognosis relates principally to the severity of the lesion. Early management must be particularly directed to the maintenance of cerebral perfusion. Later management is predominantly the therapy of posthemorrhagic hydrocephalus. There is no currently available therapeutic modality that will prevent progressive posthemorrhagic hydrocephalus.

Title Macular Cherry-red Spots and Myoclonus with Dementia: Coexistent Neuraminidase and Beta-galactosidase Deficiencies.
Date August 1978
Journal Biochemical and Biophysical Research Communications
Title An Inexpensive Modular Pulse Generating System.
Date October 1977
Journal Ieee Transactions on Bio-medical Engineering
Title The Two-course System in Gross Anatomy.
Date October 1975
Journal Journal of Medical Education
Excerpt

In response to the continuing pressures facing anatomy and other basic sciences in medical education, the Department of Anatomy at the University of Colorado School of Medicine has instituted a parallel two-course system of teaching gross anatomy. Students in both the longer and shorter of the two courses appear to be prepared adequately by their experiences in the courses they elected. Statistically significant differences (students in the longer course scoring higher) were, however, observed on both departmental examinations and certain national examinations administered subsequent to the completion of the courses. Student responses to both courses were extremely favorable. Since the differences between the two groups were generally small and advantages were noted in presenting two courses simultaneously, it is concluded that the concurrent presentation of two differently organized basic science courses (within a single subject area) offers an effective response to the instructional needs of our medical school and medical students.

Title Electrophysiological Effects of Enzymes Introduced into the Lateral Geniculate Body of the Cat.
Date August 1970
Journal Experimental Neurology
Title Neurophysiological Effects of Tetrodotoxin in Lateral Geniculate Body and Dorsal Hippocampus.
Date October 1969
Journal Brain Research
Title Effects of Tetrodotoxin on Impedance in Normal and Asphyxiated Cerebral Tissue.
Date March 1969
Journal Experimental Neurology
Title Divalent Cations in Cerebral Impedance and Cell Membrane Morphology.
Date March 1969
Journal Experimental Neurology
Title Periventricular Cerebral Impedance After Intraventricular Injection of Calcium.
Date January 1967
Journal Science (new York, N.y.)
Excerpt

Injection of small volumes of calcium solution into the lateral ventricle of the cat wa followed by large electrical-impedance changes in gray matter bounding the ventricle, including the caudate nucleus and hippocampus. These changes lasted more than 24 hours and were accompanied by epileptiform electroencephalographic activity. Biweekly injections led to status epilepticus. Injections of similar amounts of magnesium ions were without comparable effects. Possible interactions between calcium ions and intercellular macromolecular material are discussed as a basis for certain impedance shifts in cerebral tissue.


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