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Biomedical subjects

C J Limb

Publications and source records attributed to C J Limb.

7 recordsLinked to original sources
PubMed2005

Benign positional vertigo after cochlear implantation.

OBJECTIVE: To identify patients who underwent cochlear implantation (CI) and who subsequently developed benign positional vertigo (BPV) after the procedure and to identify any contributing factors. STUDY DESIGN AND SETTING: Academic tertiary referral center. Cochlear implant recipients' medical records were retrospectively reviewed to identify patients with both vertigo and, more specifically, BPV. Preoperative, intraoperative, and postoperative factors were studied vis-a-vis the development of BPV. RESULTS: BPV was newly diagnosed in 12 patients after CI. The etiology of hearing loss included presbycusis (16.6%), autoimmune inner ear disease (16.6%), congenital hearing loss (41.6%), Meniere's disease (8.3%), prematurity (8.3%), and idiopathic factors (8.3%). The onset of BPV varied after the procedure (mean +/- SD, 292 +/- 309 days). BPV symptoms did not affect implant performance. All patients were treated for BPV by Epley's maneuver and vestibular exercises. Symptoms disappeared in 11 patients and persisted in 1. CONCLUSIONS: BPV is an uncommon development after CI, although it occurs more frequently than in the general population. Two theories are proposed: the introduction of bone dust into the labyrinth and the dislodging of otoconia during surgery. The diagnosis, treatment, and prognosis of BPV after CI do not differ from those for non-CI-associated BPV. SIGNIFICANCE: Dizziness after CI usually develops as a result of vestibular hypofunction. BPV, which is a hyperfunctioning form of vestibular dysfunction, should be recognized as a possible sequelae of CI.

Adult↗
PubMed2000

Intracanalicular schwannoma of the facial nerve: a manifestation of neurofibromatosis type 2.

Primary facial nerve tumors, which are relatively uncommon, can present a diagnostic dilemma based on their location and variable pattern of symptoms. Of primary cranial nerve tumors, schwannomas of the facial nerve rank third in frequency after those of the eighth and fifth cranial nerves. We report an illustrative case of an intracanalicular schwannoma associated with several central nervous system tumors, consistent with neurofibromatosis type 2. Initially assumed to be an eighth cranial nerve tumor, the schwannoma was found intraoperatively to arise from the facial nerve. Early diagnosis and treatment enabled excision of the tumor without sacrifice of the facial nerve. Facial nerve schwannomas can resemble acoustic schwannomas in their clinical presentation. Only a heightened level of clinical vigilance will point to the correct diagnosis and result in an optimal therapeutic outcome for patients with these rare tumors.

Cranial Nerve Neoplasms↗
PubMed2000

Development of primary axosomatic endings in the anteroventral cochlear nucleus of mice.

The endbulb of Held is a large synaptic ending that arises from the myelinated auditory nerve fibers. Endbulbs exhibit an elaborate pattern of terminal branching and produce extensive contact with the postsynaptic cell body. These structural features appear to underlie the tight coupling between presynaptic activity and postsynaptic spike discharges. As a first step toward understanding the relationship between environmental sounds and the development of these neural elements, we examined the age-related changes in the morphology of endbulbs of Held in CBA/J mice, a strain known to retain good hearing throughout life. Neurobiotin was injected into the modiolus of the cochlea in CBA/J mice ranging in age from postnatal day 1 to 7 months. Light microscopic analyses suggest that endbulbs of the CBA/J mice develop from small bouton endings at birth into large, highly branched structures in adults. This increase in structural complexity occurs mostly during the second through eighth postnatal weeks, and general stages of development can be defined. In addition, we compared endbulb structure between adult CBA/J mice and adult shaker-2 mice (Myo15sh2/sh2) and heterozygous littermates (Myo15+/sh2). The shaker-2 mouse carries a mutated myosin 15 gene that results in congenital deafness, presumably due to abnormally short stereocilia in hair cell receptors. Neurobiotin was injected into the modiolus of adult CBA/J, Myo15sh2/sh2, and Myo15+/sh2 mice. Endbulbs of deaf adult Myo15sh2/sh2 mice exhibited a striking reduction in terminal branching compared with those of CBA/J and Myo15+/sh2 mice. Notably, the abnormal endbulbs of Myo15sh2/sh2 mice do not resemble immature endbulbs of normal-hearing mice, suggesting that deafness does not simply arrest development.

Aging↗
PubMed1999

Comparison of optokinetic nystagmus elicited by full versus partial visual field stimulation: diagnostic implications.

Optokinetic nystagmus (OKN) testing is one method to determine central vestibular dysfunction. OKN may be elicited by partial visual field stimulation with a light bar (OKN-ENG) or by full visual field stimulation with rotating stripes in a rotational chair test booth (OKN-RVT). OKN-ENG and OKN-RVT were elicited in 36 healthy subjects and 48 patients with known peripheral or central vestibular disorders. Abnormal test results suggested central pathology in 29 of 36 healthy subjects with OKN-ENG versus 1 of 36 with OKN-RVT. Twenty-eight of 33 patients with peripheral pathology demonstrated abnormal OKN-ENG findings, whereas 4 of 33 had abnormal OKN-RVT results. Thirteen of 15 patients with central vestibular disorders had abnormal OKN-ENG, whereas 7 of 15 had abnormal OKN-RVT. Sensitivity and specificity of OKN-ENG were 86.7% and 17.4% versus 46.7% and 92.7%, respectively, for OKN-RVT. These findings were statistically significant (P < 0.00001). OKN elicited by full visual field stimulation (OKN-RVT) is a more accurate indicator of central disease than OKN elicited by partial visual field stimulation (OKN-ENG). The use of OKN-ENG to identify central vestibular dysfunction is questionable.

Adult↗
PubMed1994

Anencephaly: changes in prenatal detection and birth status, 1972 through 1990.

OBJECTIVE: We assessed at a large university hospital the effect of prenatal diagnosis on the birth of infants with anencephaly between 1972 and 1990. STUDY DESIGN: All 175 affected infants were identified by a postnatal Malformations Surveillance Program, which included stillborn infants and elective terminations in the second trimester. The affected infants were subdivided into those whose mothers had always planned delivery at this hospital (nontransfers) and those whose mothers had planned delivery elsewhere but were transferred after the prenatal detection of the fetal abnormality (transfers). RESULTS: In the 1970s half the infants were anencephaly were born alive; the average gestational age was 35.6 weeks, and only a few were diagnosed prenatally. By 1988 to 1990 all affected infants were diagnosed either by prenatal ultrasonography or as the result of maternal serum alpha-fetoprotein screening; the parents elected to terminate the pregnancies, and the average gestational age was 19.6 weeks. CONCLUSION: Prenatal detection and the selection by parents of the option of elective termination of pregnancy has altered significantly the birth status of infants with anencephaly since 1972.

Abortion, Induced↗