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Biomedical subjects

M Koby

Publications and source records attributed to M Koby.

7 recordsLinked to original sources
PubMed1999

Pituitary involvement by Wegener's granulomatosis: a report of two cases.

We describe two cases of pituitary involvement by Wegener's granulomatosis. At initial presentation, or during subsequent disease "flares," a pattern of pituitary abnormality was suggested. During periods of remission, we found the pituitary returned to a nearly normal appearance. Loss of the normal posterior pituitary T1 hyper-intensity matched a clinical persistence of diabetes insipidus, suggesting there is permanent damage to this structure by the initial disease process.

Adolescent↗
PubMed1998

Cognitive screening examinations for silent cerebral infarcts in sickle cell disease.

OBJECTIVE: In children with sickle cell disease (SCD), silent cerebral infarcts are the most frequent cause of neurologic injury. We determined the sensitivity and specificity of selective neurocognitive measures when separating children with silent cerebral infarcts and SCD from sibling controls. Additionally, we tested the validity of the same cognitive measures to identify patients with overt strokes. METHODS: We examined performance on a neuropsychologic battery containing measures of attention/executive, spatial, language, memory, and motor functioning for seven children with SCD and silent cerebral infarct, 21 children with SCD and overt stroke, and 17 normal siblings. Diagnosis of cerebral infarct was based on results of MRI. RESULTS: Measures from the attention and executive domains were the most useful for identifying children with silent cerebral infarct. The Test of Variables of Attention was the most robust measure and yielded a sensitivity rate of 86% and a specificity rate of 81%. This measure also showed a sensitivity rate of 95% in identifying overt stroke. CONCLUSIONS: Brief cognitive screening measures, if properly constructed, may be an effective means of identifying children with silent cerebral infarct. Future prospective studies should be pursued to assess the utility of cognitive screening for silent cerebral infarcts in SCD.

Adolescent↗
PubMed1997

Associative learning in children with perinatal brain injury.

Associate learning for visual nonverbal and auditory verbal items was examined in 21 children with spastic diplegic cerebral palsy (SDCP) and 28 healthy children using four paired associate tasks. SDCP children showed poorer performance than the comparison group for learning pairs that required visual nonverbal responses, regardless of the stimulus modality. Within the SDCP group, lesion severity was assessed in 17 of the children. Lesion severity was related to the level of performance on paired associate tasks requiring visual nonverbal responses; lesion severity did not reach statistical significance for tasks requiring auditory verbal responses. The study suggests: (1) periventricular white matter regions are important for the development of basic learning processes, such as associative learning, and (2) learning of visual nonverbal material is disproportionately affected following white matter injury early in life.

Adolescent↗
PubMed1996

Prevalence and mechanisms of hearing loss in patients with resistance to thyroid hormone.

Hearing impairment was anecdotally reported in resistance to thyroid hormone (RTH), a condition caused by mutations in the beta-thyroid hormone receptor (beta TR) gene. Because of its ontogenic distribution in the cochlea, the beta TR may have a pivotal role in the development of auditory function. To assess the prevalence and mechanisms of hearing impairment in RTH, 82 RTH-positive (RTH+) patients and 55 unaffected relatives (RTH-) underwent systematic audiological examination, including puretone and speech reception thresholds, and tests studying middle ear (tympanometry and acoustic reflexes), cochlear (otoacoustic emissions), and retrocochlear integrity (brain stem auditory evoked potentials). Significant hearing loss was present in 21% of RTH+ patients vs. none in RTH- patients. More RTH+ patients had abnormal tympanometry (34% vs. 12%) and abnormal acoustic reflexes (39% vs. 19%). Isolated conductive deficit was found in 7 of 17 RTH+ patients with hearing loss, isolated sensorineural deficit in 7 cases, and mixed deficit in 3 cases. Cochlear dysfunction was found in 50% of all RTH+ patients, with or without hearing loss. Retrocochlear function was normal. No morphological cochlear abnormalities were detected on computed tomography of the temporal bone. In conclusion, hearing loss is a significant problem in RTH, with an equal frequency of conductive (probably related to the frequent ear infections) and sensorineural deficits. Abnormal otoacoustic emissions suggest that the mutant beta TR has a specific negative impact on cochlear function.

Adult↗
PubMed1996

Morphing radiologic images: applications on a desktop computer.

OBJECTIVE: Morphing is an image processing technology that transforms one image into another by generating a series of intermediate synthetic images. The ability to perform morphing, once restricted to high-end graphics workstations, is now widely available for desktop computers. We investigated the potential use of morphing for displaying radiographic images. MATERIALS AND METHODS: Morphing was performed with commercially available software (Morph 2.5; Gryphon Software, San Diego, CA) on a Macintosh (Apple Computer, Cupertino, CA) computer. Images from 26 patients with serial radiologic studies were selected, digitized, and morphed. Key points and key surfaces were identified on the images to improve the quality of the morph movie, a process that took approximately 15 min. The images were then morphed into a continuous Quick Time (Apple) movie lasting 5-7 sec. When a sequence contained more than two images, a single movie incorporating all the images was created. The intervals between segments of the movie were made proportional to the actual time elapsed between the images. Images obtained with different techniques (positron emission tomography and MR imaging) were also morphed. Three observers judged the quality of the morph movies as satisfactory, good, or excellent. RESULTS: Twenty of the 26 movies were judged to be of good or excellent quality. The movie format allowed the rapid display of multiple images in a concise 5- 7-sec time frame. Moreover, the movie allowed the recognition of several simultaneous processes more easily than was possible with static images. Morphing two images of the same anatomic site using different techniques (MR imaging and positron emission tomography) proved to be a simple method of superimposing images. CONCLUSION: Morphing is a readily available and easily learned technique for displaying serial studies. The movie format is a more interesting, intuitive, and concise summary of events than can be provided by serial static images. Morphing may be useful for displaying large numbers of serial images in a short time for occasions such as clinical conferences or teaching purposes.

Humans↗
PubMed1995

Fast spin-echo magnetic resonance imaging for radiological assessment of neonatal brachial plexus injury.

Neurosurgical management of birth-related brachial plexus palsy involves observing the patient for a period of several months. Operative intervention is usually undertaken at 3 to 6 months of age or more in infants who have shown little or no improvement in affected muscle groups. Ancillary tests such as electromyography and nerve conduction studies are occasionally useful. No radiological study has been consistently helpful in operative planning, except for contrast computerized tomography (CT) myelography, which requires general anesthesia in infants. This is because the infant's small size exceeds the functional resolution of the imaging modalities. This report describes the use of a special sequence of magnetic resonance (MR) imaging entitled "fast spin echo" (FSE-MR). Unlike CT myelography, this technique provides high-speed noninvasive imaging that allows clinicians to evaluate preganglionic nerve root injuries without the use of general anesthesia and lumbar puncture. The utility of this technique is illustrated in three cases, two involving either infraclavicular exploration or a combination of infraclavicular and supraclavicular exposure based on FSE-MR findings. The FSE-MR imaging offers an excellent alternative to contrast CT myelography in evaluation of infants with birth-related brachial plexus injuries.

Birth Injuries↗