Biomedical subjects

H A Jenkins

Publications and source records attributed to H A Jenkins.

At least 19 recordsLinked to original sources

PubMed1992

Histopathology of the temporal bone following multichannel cochlear implantation.

The temporal bone histopathologic findings of a patient having received a Nucleus 22-channel cochlear implant (Cochlear Corp, Englewood, Colo) following bilateral transverse otic capsule fractures is presented. The case was complicated by perilymph fistulas, labyrinthitis, meningitis, and death due to drowning. The left cochlea revealed complete labyrinthitis ossificans; the implanted right cochlea demonstrated new bone formation in the basal turn of the scala tympani, degeneration of the organ of Corti, but normal ganglion cell counts. Results of psychophysical and speech perception 4 months after implantation are presented.

Adult↗

PubMed1992

Characterization of glutamine metabolism in two related murine hybridomas.

Aspects of glutamine metabolism were examined in two related hybridomas, a high-producing line (PQX B1/2) and a low-producing line (PQX B2/2). The growth and metabolic characteristics of both cell lines were identical or very similar. During batch growth glutamine was completely exhausted from the medium and an examination of the fate of [14C]glutamine highlighted the importance of this amino acid as an energy source. The relative enzyme activities and the amount of ammonia produced during growth indicated that glutamine is oxidized preferentially via the transamination pathway. The overall rate of glutamine utilization from the growth medium was similar to the rate of [14C]glutamine uptake which suggests that transport may regulate glutamine metabolism.

Animals↗

PubMed1992

Temporal bone histopathology of a patient with a nucleus 22-channel cochlear implant.

The temporal bone histopathology of a patient with profound sensorineural hearing loss attributable to cochlear otosclerosis is presented. The patient had a Nucleus 22-channel cochlear prosthesis implanted in the right ear prior to his demise. Unintentional scala media insertion of the electrode array resulted from labyrinthitis ossificans obliteration of the scala tympani. Inadvertent facial nerve stimulation necessitated program exclusion of electrodes 11 to 16 located in proximity to the labyrinthine and geniculate segments of the facial nerve. The patient received significant benefit from use of the device. The histopathologic findings are correlated with psychophysical and speech perception results.

Cochlear Diseases↗

PubMed1979

Modification of constant optokinetic nystagmus by vestibular stimuation.

Experiments were conducted to quantify the effect of a vestibular stimulation of known magnitude on a constant optokinetic nystagmus (OKN). Ten normal human subjects were tested with varying magnitudes of vestibular stimuli that were superimposed on a constant 30 degrees optokinetic stimulus. The gain of the vestibular system in the dark was 0.42 +/- 0.11, and the gain in the light during superimposition testing was 0.12 +/- 0.02. From these results, predictions were made that the degree of vestibular imbalance necessary to produce an asymmetric OKN would generate a spontaneous nystagmus in the dark, which would be equivalent to 20 to 30 degrees. Data from a large group of patients were used for corroboration of the results.

Adult↗

PubMed1979

Neurogenic sarcoma of the head and neck.

We discuss our experience in the diagnosis and management of seven cases of neurogenic sarcomas of the head and neck. These uncommon tumors, which affect all ages, arise most frequently from the brachial plexus, sympathetic chain, and the cranial nerves or their branches. An enlarging mass is the most common initially appearing symptom. Diagnosis may be difficult and rests heavily on gross evidence of a relationship between the tumor and its nerve of origin. Histologically, the lesions are composed of spindle cells with varying degrees of pleomorphism in a pattern that is frequently undistinguishable from fibrosarcomas. Ultrastructural studies may be helpful in establishing the neurogenic origin of these tumors. Neurogenic sarcoma of the head and neck has an extremely poor prognosis. Surgery remains the cornerstone of treatment, although radiotherapy is important for palliation.

Accessory Nerve↗

PubMed1979

Visual-vestibular interaction and cerebellar atrophy.

The vestibular and optokinetic ocular control systems were studied in 10 patients with cerebellar atrophy and in 10 normal subjects using (1) constant velocity optokinetic stimulation, (2) sinusoidal rotation in the dark, and (3) sinusoidal rotation in the light with a surrounding fixed optokinetic drum. The gain (maximum slow component velocity/maximum head or drum velocity) of induced nystagmus was calculated from electro-oculographic recordings. Optokinetic nystagmus was abnormal in seven patients and the average optokinetic gain in the patients was significantly (p less than 0.01) less than that of the normal group. Three patients with "clinically pure" cerebellar atrophy had increased vestibular responses, and one patient with clinical signs of peripheral neuropathy had decreased responses, probably due to associated vestibular nerve disease. The average vestibulo-ocular reflex gain in patients did not differ significantly from controls (p greater than 0.05). Three patients had normal vestibular and optokinetic responses when tested independently, but had abnormal visual-vestibular interaction. These patients probably had selective disorders of the midline cerebellar pathways that mediate visual-vestibular interaction. By studying each system, both independently and during interaction, all patients were identified as abnormal, and a more precise anatomic localization of the atrophy was obtained.

Adolescent↗

PubMed1979

A technique for pharyngeal reconstruction in heavily irradiated patients.

A technique for esophageal reconstruction using a staged deltopectoral tubed, pedicled flap has been highly successful in irradiated patients. The basic principle involves use of the neck skin as the posterior wall and the dorsal and lateral aspects of the tubed flap to form the anterior and lateral walls of the newly constructed pharynx. The ventral surface forms the cutaneous covering. The submental area and base of tongue are used for implantation of the distal end of the flap, taking advantage of the abundant blood supply of this area. It is a fail-safe method of reconstruction, particularly applicable in cases in which the local skin is of poor quality.

Female↗

PubMed1979

Slow build-up of optokinetic nystagmus associated with downbeat nystagmus.

Eye movement recordings in two patients with downbeat nystagmus demonstrated an unusual finding of severely impaired smooth pursuit and relatively unimpaired optokinetic nystagmus (OKN). OKN was characterized by a remarkable, slow build-up of slow-component velocity, similar to that found in afoveate animals. Optokinetic after-nystagmus (OKAN), or transient persistence of nystagmus after cessation of visual stimulation, typical of the optokinetic response of normal human subjects, was also preserved in these patients. These observations suggest that the normal contribution of smooth pursuit to the ocular motor response to rotation of the visual environment can be selectively removed by a lesion at the level of the craniocervical junction.

Adult↗

PubMed1978

Ethmoidal mucoceles.

Twenty ethmoidal mucoceles were treated and observed for a minimum of two years after surgery. Unilateral exophthalmos was the initial complaint in all cases and nasal polyposis was a noteworthy finding in more than half of the patients. The lesions always extended into the orbit and usually eroded the floor of the frontal sinus. Exenteration through an ethmoidectomy approach was successful in 16 cases. Failure was due to recurrence of the mucocele in one case and in three cases to uncontrolled polypoid disease that produced recurrence of the exophthalmos. Long-term follow-up is mandatory since recurrences may take several years to occur.

Adolescent↗

PubMed1978

Linear model for visual-vestibular interaction.

The results of experiments are evaluated in terms of a simple model for the interaction of eye movement responses to simultaneous optokinetic and vestibular stimuli. The model predictions agree with the results of these experiments and explain many clinical observations concerning the effect of vision on nystagmus. The model accounts for the dominance of the visual system's response over the vestibular system's response at low frequencies. It also accounts for the inability of patients with decreased smooth pursuit system response to suppress the vestibulo-ocular reflex during simultaneous optokinetic and vestibular stimulations. The model provides useful information for the design of combined optokinetic and vestibular stimuli for test vestibulo-ocular reflexes.

Eye Movements↗

PubMed1978

Vestibular-optokinetic interactions in normal subjects and in patients with peripheral vestibular dysfunction.

The vestibulo-ocular reflex (VOR) during rotation, optokinetic nystagmus (OKN), and interactions between the vestibulo-ocular and optokinetic systems were studied quantitatively in 10 normal human subjects, 15 patients with unilateral horizontal semicircular canal paralysis (UP), and 11 patients with bilateral horizontal semicircular canal paralysis (BP). The OKN gain (eye velocity/drum velocity) was not significantly different between the normal subjects and the patient groups. During tests in which rotatory and visual stimuli were presented simultaneously, the contribution to the observed eye movements by the VOR was only one-fourth to one-third of its gain during rotation in the dark in the normal subjects and UP patients. These interactive tests did not differentiate UP patients from normal subjects but did separate BP patients from normal subjects.

Adult↗

PubMed1978

The spectrum of audiologic and vestibular findings in patients with Meniere's disease.

A retrospective study of 55 patients with Meniere's disease suggested a subgrouping based on presentation of auditory symptoms. Patients were defined as "definite" (documented fluctuating hearing loss and episodic vertigo), "probable" (history of fluctuating hearing loss and episodic vertigo) and "possible" (history of fluctuating tinnitus and episodic vertigo). An in-depth discussion of the natural history, audiometric and vestibular findings is presented.

Adult↗

PubMed1977

Management of brachial plexus tumors.

Brachial plexus neoplasms are uncommon. When this diagnosis is suspected, the functional and anatomical integrity of the brachial plexus and cervical spinal cord must be carefully assessed. A thorough search for other signs of neurofibromatosis (von Recklinghausen's disease) must also be completed. The distinction between neurilemoma and neurofibroma is an important and useful one to know. Evaluation by a pathologist who is well versed in neural tumors is mandatory for appropriate treatment of these usually benign lesions. Surgical intervention, adequately prepared on the basis of the patient's age, the amount of neural impairment, and the extent and histology of the tumor requires a surgeon who is experienced in peripheral nerve surgery and in microdissection techniques. Long-term follow-up is necessary to monitor the growth of known tumors, the detection of malignant change, and the appearance of other stigmata of von Recklinghausen's disease.

Adolescent↗

PubMed1976

Porencephalic cyst of the mastoid.

A 10-year-old boy developed a porencephalic cyst of the mastoid in conjunction with otitic meningitis and cerebrospinal otorrhea. A defect of the tegmen tympani allowed extrusion of the cyst into the antrum and the mesotympanum. The otorrhea was controlled by closure of the defect. Our review of 251 cases in the literature showed no prior incidence of mastoid involvement by a porencephalic cyst.

Brain Diseases↗

PubMedDate not supplied

Melanoma of the conjunctiva--a rational approach to management.

Eleven of 12 patients treated for invasive melanomas of the conjunctiva at the UCLA Hospitals from 1955 to 1976 revealed data sufficient for evaluation. Of these 11 cases, 4 died from 3 to 13 years after treatment as a result of the disease. The plan presented for surgical management of melanosis is based on histologic criteria and on the anatomic location of the tumor. In this series, such management ranged from local excision of noninvasive melanotic lesions to orbital exenteration with parotidectomy and radical neck dissection for invasive melanomas that involved the palpebral conjunctiva or caruncle. Extended follow-up is needed in all patients.

Adult↗

PubMedDate not supplied

Diagnosis and treatment of carotid body tumors.

The diagnosis and management of carotid body tumors are discussed, including the importance of good arteriography which allows visualization of all major feeding vessels. These include the carotid bulb, internal and external carotid arteries and the often neglected but important vertebral and ascending cervical arteries. Emphasis is placed on the importance of establishing tourniquet control of the common, internal and external carotid arteries. Surgeons removing carotid body tumors should be experienced in arterial wall repair by means of vascular shunts, end-to-end arterial anastomosis, and vein graft replacement of a segment of arterial wall.

Angiography↗

PubMedDate not supplied

Acute laryngeal abscesses.

The clinical features of laryngeal abscess have changed markedly since the introduction of antibiotics and are rarely seen by clinicians today. Three cases of acute laryngeal abscess associated with malignancy, airway instrumentation and a preexisting laryngocele respectively are presented. Management of these cases included immediate tracheostomy, intravenous antibiotics and surgical drainage. Current etiological factors and modes of presentation are discussed. Laryngeal abscess remains a serious and potentially lethal problem requiring emergent treatment. Serious sequelae may result from this disease.

Abscess↗

PubMedDate not supplied

Computerized tomography scanning of the temporal bone.

Computerized tomography (CT) scanning has reached a degree of sophistication that requires alteration of technical factors to demonstrate different parameters of temporal bone pathology. The techniques for pontocerebellar angle display, eustachian tube, middle ear pathology, and overall temporal bone display are quite different. Close cooperation between the radiologist and otologic surgeon are required for optimal use of CT scanning advances.

Adult↗