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Biomedical subjects

Y S Hahn

Publications and source records attributed to Y S Hahn.

At least 55 records · Page 3Linked to original sources
PubMed1989

Paraplegia resulting from thoracolumbar stenosis in a seven-month-old achondroplastic dwarf.

In young achondroplastic children, neurological manifestations have been found to include macrocephaly, hydrocephalus or ventriculomegaly and cervicomedullary compression. Occasionally in the second decade, lumbar radiculopathy or paraparesis resulting from severe thoracolumbar kyphosis develops. In this paper, we report the unique case of an achondroplastic dwarf who developed paraplegia due to thoracolumbar spinal cord compression at the age of 7 months. Compromise of the spinal canal was found to be due not to bony stenosis, but to a second layer of fibrous tissue, histologically identical to the dura. Treatment consisting of decompressive laminectomy and resection of the constricting tissue allowed the child to recover completely. Clinical, radiographic and pathological findings are discussed.

Achondroplasia↗
PubMed1988

Head injuries in children under 36 months of age. Demography and outcome.

Head injuries in children under the age of 3 years have not been extensively studied, due in part to the lack of an objective tool for neurological assessment. We have developed a Children's Coma Scale (CCS) by modifying the verbal response subscore of the Glasgow Coma Scale (GCS) to overcome this limitation. When applied prospectively to children under 3 years of age, we found the CCS to be useful in predicting outcome. During the 5-year study period from 1981 to 1985, there were 738 patients with head injuries (0-16 years) admitted to the Children's Memorial Hospital in Chicago, including 318 (43.1%) less than 3 years of age. Initial data demonstrated the following observations. The most common mechanism of injury was a fall (75.5%). Although a brief loss of consciousness (LOC) was reported in three-fourths of the patients, prolonged LOC of more than 6 h was uncommon (16/318, 5.0%). The classically described "lucid interval" was seen in only 7 children (2.2%) and was not a reliable indicator of epidural hematoma. Post-traumatic seizures developed more commonly in children under 2 years of age (15.7%) than in older children (11.6% under 3 years of age, 9.6%, entire group), (P less than 0.001). Oculovestibular reflex and bilateral fixed dilated pupils had the most reliable correlation with outcome. Other brain-stem reflexes were less useful.(ABSTRACT TRUNCATED AT 250 WORDS)

Cause of Death↗
PubMed1988

Nucleotide sequence of dengue 2 RNA and comparison of the encoded proteins with those of other flaviviruses.

We have determined the complete sequence of the RNA of dengue 2 virus (S1 candidate vaccine strain derived from the PR-159 isolate) with the exception of about 15 nucleotides at the 5' end. The genome organization is the same as that deduced earlier for other flaviviruses and the amino acid sequences of the encoded dengue 2 proteins show striking homology to those of other flaviviruses. The overall amino acid sequence similarity between dengue 2 and yellow fever virus is 44.7%, whereas that between dengue 2 and West Nile virus is 50.7%. These viruses represent three different serological subgroups of mosquito-borne flaviviruses. Comparison of the amino acid sequences shows that amino acid sequence homology is not uniformly distributed among the proteins; highest homology is found in some domains of nonstructural protein NS5 and lowest homology in the hydrophobic polypeptides ns2a and 2b. In general the structural proteins are less well conserved than the nonstructural proteins. Hydrophobicity profiles, however, are remarkably similar throughout the translated region. Comparison of the dengue 2 PR-159 sequence to partial sequence data from dengue 4 and another strain of dengue 2 virus reveals amino acid sequence homologies of about 64 and 96%, respectively, in the structural protein region. Thus as a general rule for flaviviruses examined to date, members of different serological subgroups demonstrate 50% or less amino acid sequence homology, members of the same subgroup average 65-75% homology, and strains of the same virus demonstrate greater than 95% amino acid sequence similarity.

Amino Acid Sequence↗
PubMed1988

Scalp and calvarial masses of infants and children.

Review of 70 children presenting with a solitary nontraumatic lump on the head revealed that 61% of the lesions were dermoid tumor, 9% were cephalhematoma deformans, 7% were eosinophilic granuloma, and 4% were occult meningoceles and encephaloceles. Most of the dermoid cysts occurred along sutural lines, but some did not. One of the eosinophilic granulomas was located over the sagittal suture. Seventeen per cent of the "lumps" had significant intracranial extension. An additional 20% of the lumps extended intracranially, but only to the dura mater. Work-up of these lesions should include initial plain skull roentgenograms to assess multiplicity and appropriate computed tomographic scans to assess possible intracranial extension.

Adolescent↗
PubMed1988

Factors influencing posttraumatic seizures in children.

The ideal treatment of children with head trauma would include prevention of posttraumatic seizures. Ninety-two of 937 children with head injuries (9.8%) experienced posttraumatic seizures. In 94.5% of these patients (87 of 92), seizures developed within the first 24 hours after injury. Three children convulsed between 24 hours and 7 days, but only 2 children developed seizures after the 1st week. Factors found to influence the likelihood of seizures included severe head injury (GCS, 3 to 8), diffuse cerebral edema, and acute subdural hematoma (P less than 0.001). Seizures occurred in 35% of severely head-injured children compared to 5.1% with minor head injury (P less than 0.001). A less significant correlation (P less than 0.1) was noted between seizures and open, depressed skull fractures. We found no significant correlation between seizure occurrence and numerous other factors including age, sex, fracture location and type (other than open, depressed fractures), parenchymal injuries, fixed neurological deficits, and cranial operation. Based on our observations, we recommend the prophylactic use of anticonvulsants in children at higher risk for posttraumatic seizures: those with diffuse cerebral edema, acute subdural hematoma, open, depressed skull fracture with parenchymal damage, or severe head injury (GCS less than or equal to 8).

Adolescent↗
PubMed1987

Conserved elements in the 3' untranslated region of flavivirus RNAs and potential cyclization sequences.

We have isolated a cDNA clone after reverse transcription of the genomic RNA of Asibi yellow fever virus whose structure suggests it was formed by self-priming from a 3'-terminal hairpin of 87 nucleotides in the genomic RNA. We have also isolated a clone from cDNA made to Murray Valley encephalitis virus RNA that also appears to have arisen by self-priming from a 3'-terminal structure very similar or identical to that of yellow fever. In addition, 3'-terminal sequencing of the S1 strain of dengue 2 RNA shows that this RNA is also capable of forming a 3'-terminal hairpin of 79 nucleotides. Furthermore, we have identified two 20-nucleotide sequence elements which are present in the 3' untranslated region of all three viruses; one of these sequence elements is repeated in Murray Valley encephalitis and dengue 2 RNA but not in yellow fever RNA. In all three viruses, which represent the three major serological subgroups of the mosquito-borne flaviviruses, the 3'-proximal conserved sequence element, which is found immediately adjacent to the potential 3'-terminal hairpin, is complementary to another conserved domain near the 5' end of the viral RNAs, suggesting that flavivirus RNAs can cyclize (calculated delta G less than -11 kcal; 1 kcal = 4.184 kJ).

Base Sequence↗
PubMed1987

Cervical intervertebral disc calcification in children.

Intervertebral disc calcification in children is a rare occurrence. The clinical symptoms and signs are distinctively confined to the cervical area with pain, limitation of motion, and torticollis. Long tract signs or radicular involvement are extremely unusual. CT scan and cervical spinal X-ray films shown the calcification to be in the nucleus pulposus with anterior or posterior mild protrusion into the spinal canal. Recovery without neurological sequelae is the rule in most of the pediatric cases with conservative treatment. Intervertebral disc calcification does not necessarily disappear with the onset of clinical symptoms. A case with persistent and even denser calcification at the same level of intervertebral disc space at the second episode of recurrence is illustrated.

Calcinosis↗
PubMed1987

Traumatic bilateral ophthalmic artery aneurysms: a case report.

A case of bilateral ophthalmic artery aneurysm of traumatic origin is discussed. The patient presented with progressive loss of vision, memory deficit, and expressive aphasia. A computed tomographic scan revealed enhancing lesions near the region of the optic chiasm. The diagnosis of cerebral aneurysm was confirmed by cerebral angiography. At operation, bilateral ophthalmic artery aneurysms were successfully clipped.

Aneurysm↗
PubMed1987

Brain herniation and space-occupying lesions eroding the tegmen tympani.

Technological advances in neuroradiology and the development of skull base surgery in neurotology have improved diagnosis and management of lesions eroding the tegmen tympani. The diagnosis of brain hernia is to be suspected in patients with a history of complicated chronic ear surgery and a slowly developing pulsatile mass with CSF leak. Patients are best evaluated in the upright position, with an otomicroscope and by magnetic resonance imaging (MRI). Over 6 years, our group has treated seven patients with eight space-occupying lesions eroding the tegmen. Five of the lesions were repaired with a temporalis muscle flap, 2 with fascia and bone, and 1 with Marlex. A review of new technology in the diagnosis of brain hernia and a modification of previous techniques is given.

Adolescent↗
PubMed1986

Successful reinnervation of the diaphragm after phrenic nerve transection.

A 16-month-old infant presented with bilateral diaphragmatic paralysis and respiratory failure after removal of a thoracic teratoma. Right diaphragmatic function recovered after end-to-end anastomosis of a transected phrenic nerve. We conclude that phrenic nerve repair can restore diaphragmatic function and should be attempted in selected cases of diaphragmatic paralysis due to phrenic nerve injury.

Diaphragm↗
PubMed1983

Work in progress. Intraoperative neurosurgical ultrasound: localization of brain tumors in infants and children.

Intraoperative real-time ultrasonic sector scanning was performed through the unincised dura mater or the intact brain surface of eight patients (aged six months to 13 years), each of whom had a previously documented mass lesion (four supratentorial, three infratentorial, one intraventricular). In each case, there was a clear definition of the location, configuration, and tissue consistency of the mass. With the exception of a choroid plexus papilloma, all lesions demonstrated both solid and fluid components. The location of a subcortical parietal lobe mass (ependymoma) was apparent only by prior sonography. All neoplastic tissue of one cerebellar astrocytoma that was identified at gross examination was removed, but additional intraoperative scanning following removal of the neoplasm suggested the presence of residual abnormal tissue. This was confirmed during further exploration, and additional gross tumor tissue was excised.

Adolescent↗
PubMed1983

Traumatic mechanisms of head injury in child abuse.

Child abuse is a complex sociophysical phenomenon in which a child may suffer physical and mental assault ranging from death to emotional deprivation. In this report, an effort is made to identify the pathogenetic mechanisms of head injury in child abuse and to describe the site of injury, incidence of head injury, and difficulties encountered in establishing a doctor-family relationship. During the years 1970 through 1979, 621 children were confirmed victims of child abuse and treated by the medical staff at the Children's Memorial Hospital in Chicago. Of these, there were 77 children (12%) who suffered associated head injuries ranging from cerebral concussion to irreversible brain damage and/or death. 85% of these head-injured children were under the age of 2 years. 62% were male and 38% female. In analyzing the type of injury which resulted in an associated head injury, we learned that 54% of all injuries were caused by direct blows to the head, face and other parts of the body, 35% were due to dropping, throwing or falling; only 8% were caused by 'shaking'. 55 injuries (48%) out of 115 trauma cases were thought to be caused by injury to head or face. 53 patients showed 113 external skin wounds such as ecchymoses of eyes, excoriations, bruises, contusion, hematoma, burns, etc. 46% of all external wounds were found over the head and face. This may probably indicate to us that a traumatic force causing injury to the brain is directed to the head and face. The traumatic mechanisms are analyzed and discussed to assess the behavioral derangement of the assault.

Adolescent↗
PubMed1979

An elastic pouch operation for large retinal tears.

An episcleral pouch operation that uses Dacron-reinforced silicone sheeting for the patch and silicone sponge pellets for the stuffing has been used to extend the localized radial buckling technique to retinal detachments that are caused by breaks that span a circumferential arc between 40 degrees and 70 degrees. Nineteen of 20 retinal detachments responded favorably to the operation, 14 without drainage of subretinal fluid. When the pouch was extended circumferentially to apply to detachments caused by breaks greater than 70 degrees, it failed in six of seven patients because a radial configuration could no longer be maintained. The substitution of transparent silicone sheeting for donor sclera facilitates the fitting and stuffing of the pouch.

Adolescent↗
PubMed1979

Infection after sponge implantation for scleral buckling.

In one series of 900 explant scleral buckling procedures, 31 had to be removed over seven years because of contamination. Of 1,000 explants from a parallel series, 27 had to be removed. In the second series, requirement of a sterile conjunctiva preoperatively and the use of prophylactic antibiotics postoperatively did not significantly reduce the rate of infection.

Bacterial Infections↗
PubMed1979

A temporary balloon buckle for the treatment of small retinal detachments.

An inflatable silicone explant has been used to treat small retinal detachments. The device is inserted through the conjunctiva at the oral and expanded beneath the retinal break. Subretinal fluid absorbs because the intrusion of the balloon closes the retinal break. Adhesion is obtained by transconjunctival cryopexy or laser coagulation. The balloon, which is unsecured by sutures, is deflated and withdrawn after one week.

Humans↗
PubMed1978

Intraneural hematoma of the sciatic nerve. Case report.

A case of an encapsulated organizing hematoma of the sciatic nerve is reported. Hemorrhage-induced neuropathy as a complication of anticoagulant therapy, leukemia, hemophilia, and other bleeding diatheses has been frequently reported. While trauma is the most common etiology of a hemorrhagic neuropathy, actual hematoma formation beneath the epineurium is very rare.

Hematoma↗