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P A Wackym

Publications and source records attributed to P A Wackym.

At least 19 recordsLinked to original sources
PubMed2000

Adenylyl cyclase isoforms in the vestibular periphery of the rat.

The expression of adenylyl cyclase (AC) isoforms in the adult rat vestibular periphery was investigated using reverse transcription polymerase chain reaction (RT-PCR). AC II, IV and V mRNAs were expressed in both Scarpa's ganglion and vestibular end organs. In addition, in the vestibular end organs, an AC mRNA not previously reported in the rat was identified. The cloned sequence (GenBank accession no. AF184150) represented 95 amino acids with 100% similarity to the human AC VII and 94% to the bovine AC VII. AC VII mRNA also was found in the cerebellum but was undetectable in heart, kidney, liver and Scarpa's ganglion.

Adenylyl Cyclases↗
PubMed2000

Partial cDNAs encoding G-protein alpha subunits in the rat vestibular periphery.

To begin understanding what G-proteins are involved in signal transduction in the vestibular periphery, the expression of Galpha subunits in rat primary afferent neurons (Scarpa's ganglia) and end-organs was studied. Reverse transcription-polymerase chain reaction (RT-PCR) with degenerate primers corresponding to two conserved regions of the Galpha protein coding sequence produced partial cDNAs encoding two distinct forms of Galpha(s) subunit (Galpha(s2) and anove) Galpha(s2) subunit,GenBank accession number AF1841510); and two forms of Galpha(i2) subunits. A novel truncated form of Galpha(i2) (designated Galpha(i2(vest)),Gen Bank accession number AF189020) was detected in the vestibular periphery. Galpha(i2(vest)) was also expressed in rat cerebellum and heart. The possible role of the identified Galpha protein cDNAs in the function of the vestibular periphery is discussed.

Amino Acid Sequence↗
PubMed2000

Topographic distribution of nicotinic acetylcholine receptors in the cristae of a turtle.

The neurochemical basis of cholinergic efferent modulation of afferent function in the vestibular periphery remains incompletely understood; however, there is cellular, biochemical and molecular biological evidence for both muscarinic and nicotinic acetylcholine (ACh) receptors (nAChRs) in this system. This study examined the topographic distribution of alpha-bungarotoxin (alpha-BTX) nAChRs in the cristae of a turtle species. Cristae were perfusion-fixed, cut at 20 micrometer on a cryostat and incubated with alpha-BTX or polyclonal antibodies raised against Torpedo nAChR. Light microscopy showed abundant specific labeling of nAChR in the central zone of each hemicrista on the calyx-bearing afferents surrounding type I hair cells and on the base of the type II hair cells. Within the peripheral zone, dense labeling of type II hair cells near the torus and sparse or no label was observed on type II hair cells near the planum. The alpha-BTX binding showed a similar pattern within the cristae. The similarity between the topographic distribution of alpha-BTX binding nAChR and of efferent inhibition of afferents supports the notion that the inhibitory effect of afferents is mediated by nAChR.

Afferent Pathways↗
PubMed2000

Cochlear implantation for auditory rehabilitation in Camurati-Engelmann disease.

Camurati-Engelmann disease (progressive hereditary diaphyseal dysplasia) is a rare sclerotic bone disease involving the diaphyses of the long bones, skull base, and clavicles. Progressive sclerosis of cranial nerve foramina has been implicated in cranial nerve deficits. including facial nerve palsy, vestibular disturbances, and hearing loss. Two patients with Camurati-Engelmann disease and concomitant sensorineural hearing loss are presented. Both patients were evaluated for cochlear implantation. One patient was successfully implanted after preoperative imaging revealed no involvement of the internal auditory canals. The porous nature of the affected bone, however. necessitated the inactivation of 1 electrode to prevent facial nerve stimulation. A second patient was rejected as a potential implant recipient due, in part, to narrow internal auditory canals and rapidly progressive disease. The otologic manifestations of Camurati-Engelmann disease are reviewed, and issues related to cochlear implantation in this rare disease are discussed.

Adult↗
PubMed1999

Isolated primary unilateral stenosis of the internal auditory canal.

Congenital primary stenosis of the internal auditory canal (IAC) may exist in isolation or along with a number of other osseous anomalies of the temporal bone. Most of the literature on IAC stenosis is concerned with its effect on the outcome of cochlear implantation (i.e. patients with profound bilateral hearing loss). In addition, some degree of canal asymmetry has been noted in patients with normal hearing, questioning the causal relationship of this finding to deafness. We describe two children with computed tomography (CT) documented severe primary unilateral narrowing of the IAC and an associated ipsilateral sensorineural hearing loss. Typical radiographic findings are described, and the relevant developmental pathology is discussed. The ipsilateral association of stenosis and hearing loss strengthens the link between narrowing of the IAC and deafness.

Adolescent↗
PubMed1999

Evaluation of surgical approaches to endoscopic auditory brainstem implantation.

OBJECTIVES: This study investigates the use of endoscopy for the placement of an auditory brainstem implant by translabyrinthine, retrosigmoid (suboccipital), and middle cranial fossa approaches. STUDY DESIGN: Cadaver dissection and endoscope-assisted placement of the auditory brainstem implant. METHODS: Translabyrinthine, retrosigmoid, and middle cranial fossa dissections were performed bilaterally in five cadaveric heads. An auditory brainstem implant was placed within the lateral recess of the fourth ventricle under endoscopic visualization. The implantation was performed with all approaches and documented by digital image capture followed by production of dye-sublimation photographic prints. RESULTS: The lateral recess was visualized with the endoscope in all three approaches to the brainstem. The 30 degrees endoscope provided the best visualization by translabyrinthine and retrosigmoid dissection and was essential for the middle cranial fossa approach. Refinement of implant position was readily achieved, as even the deepest portion of the recess could be seen with all three approaches. CONCLUSIONS: This study finds that endoscopy provides superior visualization of the lateral recess of the fourth ventricle than the operating microscope with all approaches. The retrosigmoid approach is recommended, as it provides the best view of the implantation site and the easiest angle for placement of the prosthesis. The use of the endoscope may allow for a smaller craniotomy than with conventional microscopic techniques, depending on tumor size. The translabyrinthine approach provides a good view of the lateral recess but had no advantage over other approaches. The middle cranial fossa approach is only possible with angled endoscopes; however, it is technically the most difficult and places the facial nerve at greatest risk.

Acoustic Stimulation↗
PubMed1999

Adjunctive use of endoscopy during acoustic neuroma surgery.

OBJECTIVE/HYPOTHESIS: In specific clinical situations, endoscopes offer better visualization than the microscope during acoustic neuroma (vestibular schwannoma) surgery and can therefore decrease the incidence of the postoperative complications of cerebrospinal fluid (CSF) leakage and recurrence of tumor. This study was undertaken to determine if the use of adjunctive endoscopy provides complementary information to the operating surgeon during surgery for acoustic neuromas. METHOD: Seventy-eight patients with acoustic neuromas underwent tumor excision by two neurotologists (PAW., D.S.P.), together with their respective neurosurgical partners, via a retrosigmoid (suboccipital) approach (n = 68), translabyrinthine approach (n = 7), or middle cranial fossa approach (n = 3). Endoscopy with a rigid glass lens endoscope was used during tumor removal to examine posterior fossa neurovascular structures, and after tumor excision to inspect the internal auditory canal (IAC), inner ear, and middle ear, depending on the approach used. One of the authors (D.S.P.) has not used adjunctive endoscopy during resections via the translabyrinthine and middle cranial fossa approaches, and therefore, these cases were excluded from the data collection and analysis. RESULTS: Complete tumor excision was achieved in 73 patients. Endoscopy allowed improved identification of tumor and adjacent neurovascular relationships in all cases. In addition, residual tumor at the fundus of the IAC (n = 11) and exposed air cells (n = 24) not seen with the microscope during retrosigmoid approaches were identified endoscopically. In one of the translabyrinthine cases, the endoscope allowed identification of open air cells not visualized with the microscope. None of the 78 patients developed CSF rhinorrhea. Incorporating the endoscope did not significantly increase operative time. CONCLUSIONS: Endoscopy can be performed safely during surgery to remove acoustic neuromas. The adjunctive use of endoscopy may offer some advantages including improved visualization, more complete tumor removal, and a lowered risk of CSF leakage.

Adolescent↗
PubMed1999

Endoscope-assisted surgery for acoustic neuromas (vestibular schwannomas): early experience using the rigid Hopkins telescope.

OBJECTIVE: Endoscopes have been increasingly used during neurosurgical procedures. Previously, they have been shown to offer better visualization than the microscope in selected situations and frequently have allowed less invasive surgery. This study was undertaken to determine whether endoscopy is safe and effective during suboccipital surgery for vestibular schwannomas. METHODS: Ten patients with vestibular schwannomas underwent suboccipital transmeatal craniotomies for tumor excision. Endoscopy with a rigid glass lens endoscope (Hopkins telescope) was used during tumor removal to examine posterior fossa neurovascular structures and after tumor excision to inspect the internal auditory canal. RESULTS: Complete tumor excision was achieved in nine patients. Endoscopy allowed improved identification of tumor and adjacent neurovascular relationships in all cases without the need for significant retraction of the cerebellum or brain stem. In addition, residual tumor at the fundus of the internal auditory canal (n = 2) and exposed petrous air cells (n = 3) not seen with the microscope were identified endoscopically. Operative time was not significantly increased by incorporating the endoscope. CONCLUSION: Posterior fossa endoscopy can be performed safely during surgery for tumor removal. Endoscope-assisted surgery for vestibular schwannomas may offer some advantages over standard microsurgery in selected cases. The advantages may include improved visualization, more complete tumor removal, and a lowered risk of cerebrospinal fluid leakage.

Adult↗
PubMed1999

A critical appraisal of spontaneous perilymphatic fistulas of the inner ear.

OBJECTIVE: This article provides an overview of relevant data supporting and refuting the existence of spontaneous perilymph fistula, as well as critically reviewing the literature pertaining to their evaluation and management. DATA SOURCES: Sources used were relevant English language clinical and basic science publications. STUDY SELECTION: A Medline search dating back to 1966 for articles concerning perilymphatic fistula, including both human and animal data, was performed. Articles were included if they contained relevant data or were significant reviews of the subject. A traditional bibliography search was then completed to acquire articles missed by the computerized search, including works published before 1966. DATA EXTRACTION: The data from each publication were critically reviewed. Emphasis on understanding the clinical features of surgically created perilymph fistulas was used to more objectively assess the data regarding spontaneous perilymph fistulas. DATA SYNTHESIS: The data were not amenable to formal meta-analysis or valid data summarization; however, when possible trends and contrasting data were emphasized. CONCLUSIONS: Spontaneous perilymph fistulas are very rare occurrences and the majority are likely incited by a pressure-altering event. Current methodologies do not provide sufficient specificity and sensitivity to accurately diagnose perilymph fistulas. The results of endoscopic studies of the middle ear in the evaluation of perilymphatic fistula suggest a low incidence compared with the large number of fistulas reported in the literature. A high index of suspicion must be maintained, and appropriate preoperative counseling should reflect the current controversies. Questions must continue to be asked and further research pursued to help distinguish reality from myth.

Fistula↗
PubMed1998

Clinical and molecular pathology of aggressive Schneiderian papilloma involving the temporal bone.

BACKGROUND: Inverting papilloma is a benign but locally aggressive sinonasal tumor that rarely involves the middle ear or temporal bone. METHODS: A report of a case and the molecular pathology of the tumor is presented. RESULTS: A 35-year-old woman with a history of recurrent inverting papilloma of the left paranasal sinuses was found to have evidence of extension through the eustachian tube and extensive involvement of the temporal bone. Surgical management resulted in the patient being disease-free at 14 months. Molecular pathology studies of the resected tumor suggest an association with human papillomavirus. CONCLUSIONS: Direct extension of the sinonasal tumor through the eustachian tube may represent the pathologic mechanism involved in the development of inverting papilloma involving the middle ear and temporal bone.

Adult↗
PubMed1998

Molecules, motion, and man.

The application of cell and molecular biology techniques to vestibular research is resulting in rapid changes in our understanding of the fundamental mechanisms of vestibular function. The clinical problems encountered in space travel together with the acute and chronic vestibular dysfunction affecting many of the patients otolaryngologists care for have driven this research at a rapid pace. A review of these methods and highlights of the major advances are discussed.

Animals↗
PubMed1998

Evidence for three additional P2X2 purinoceptor isoforms produced by alternative splicing in the adult rat vestibular end-organs.

P2X2 receptors are ligand-gated ion channels that are activated by extracellular ATP. To characterize the expression of P2X2 purinoceptor in the adult rat vestibular periphery, reverse transcription-polymerase chain reaction (RT-PCR) was used. No transcript for P2X2 receptor was found in the vestibular primary afferent neurons (Scarpa's ganglia); however, partial cDNAs encoding four splice variants of the P2X2 receptor were isolated from vestibular end-organs. In all four cDNAs, the deletions were of different lengths but started at the same position on the P2X2 gene (Val-370 codon) located toward the intracellular carboxyl terminus. One of these receptor isoforms was identical in sequence to the recently published P2X2(b) receptor (Simon et al., 1997, Mol. Pharmacol. 52, 237-248) (also known as P2X2-2, in the nomenclature of Brändle et al., 1997, FEBS Lett. 404, 294-298). The remaining three novel splice variants of the P2X2 receptor were designated P2X2(e), P2X2(f) and P2X2(g) (GenBank accession numbers AF028603, AF028604 and AF028605, respectively). The functional significance of these three splice variants remains to be determined. Pituitary and cerebellum were used as survey tissues and only the P2X2(b) receptor cDNA was found.

Alternative Splicing↗
PubMed1998

Molecular temporal bone pathology: III. Genotyping of the deltaF508 deletion in the DNA of patients with cystic fibrosis.

Genomic DNA from a single celloidin-embedded archival temporal bone section was used to identify a specific genetic mutation. The polymerase chain reaction was used to amplify and detect the deltaF508 deletion, a common molecular genetic defect in cystic fibrosis. This mutation, present in more than 70% of white patients and carriers with cystic fibrosis, results in the deletion of codon 508, which specifies the amino acid phenylalanine of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. When this technique was applied to archival specimens from four patients with cystic fibrosis, all expressed the carrier state of this defective gene. These data demonstrate the feasibility of identifying genetic mutations in archival temporal bone specimens.

Alleles↗
PubMed1998

Molecular temporal bone pathology: IV. Analysis of DNA template length using mitochondrial PCR primers.

The focus of this study was to identify, via molecular biology techniques, the length of the DNA templates present in individual archival celloidin-embedded human temporal bone sections. Earlier studies have suggested that the maximum template length present in these tissues is on the order of 471 base pair (bp). Polymerase chain reaction (PCR) amplification of 92 bp, 121 bp, 471 bp, and 609 bp regions of mitochondrial DNA (mtDNA), extracted from single archival celloidin-embedded human temporal bone sections, was used to assess the length of the template DNA extracted. These data are crucial to determine the limits of applying PCR technology to amplify specific genomic DNA targets located within the human inner ear. The results described should be of value to those investigators extracting DNA from archival individual human temporal bone sections for polymerase chain reaction assays of specific genetic alterations or infectious agents associated with temporal bone pathologies.

DNA Primers↗
PubMed1998

Endoscope-assisted vestibular neurectomy.

OBJECTIVE/HYPOTHESIS: In some instances endoscopes offer better visualization than the microscope and frequently allow less invasive surgery. This study was undertaken to determine whether endoscopy is safe and effective during neurectomy of the vestibular nerve. METHOD: Ten patients with intractable unilateral Meniere's disease underwent a retrosigmoid craniotomy for neurectomy of the vestibular nerve. Endoscopy with a Hopkins telescope was used during each procedure to study posterior fossa anatomic relationships and to assist the neurectomy. Preoperative and postoperative audiometric evaluation was performed in all patients undergoing vestibular neurectomy. Nine of these patients had preoperative electronystagmography, and four patients completed postoperative electronystagmography. The 1995 American Academy of Otolaryngology-Head and Neck Surgery's Committee on Hearing and Equilibrium guidelines for the diagnosis and evaluation of therapy in Meniere's disease were used. RESULTS: Complete neurectomy was achieved in all 10 patients. Endoscopy allowed improved identification of the nervus intermedius and the facial, cochlear, and vestibular nerves and adjacent neurovascular relationships without the need for significant retraction of the cerebellum or brainstem. In addition, endoscopic identification of the cleavage plane between the cochlear and vestibular nerves medial to or within the internal auditory canal (n = 3) was not made with the 0-degree endoscope; however, identification was made with the 30- or 70-degree endoscope in all cases. In all patients with Meniere's disease, elimination of the recurrent episodes of vertigo (n = 10) or otolithic crisis of Tumarkin (n = 1) was achieved. CONCLUSIONS: Posterior fossa endoscopy can be performed safely. Endoscope-assisted neurectomy of the vestibular nerve may offer some advantages over standard microsurgery including increased visualization, more complete neurectomy, minimal cerebellar retraction, and a lowered risk of cerebrospinal fluid leakage.

Adult↗
PubMed1997

Differential expression of alpha2-7, alpha9 and beta2-4 nicotinic acetylcholine receptor subunit mRNA in the vestibular end-organs and Scarpa's ganglia of the rat.

To further characterize the pattern of expression of the nicotinic acetylcholine receptor (nAChR) subunits in the peripheral vestibular system, we conducted RT-PCR of all known mammalian nAChR alpha and beta subunits in mRNA extracted from adult rat vestibular primary afferent neurons (Scarpa's ganglia) and vestibular end-organs. Transcripts encoding the alpha2-7 and beta2-4 nAChR subunits were found in the vestibular ganglia, while alpha3, alpha5-7, alpha9 and beta2-4 nAChR subunits were expressed in the vestibular end-organs. These results support previous electrophysiological, immunocytochemical and molecular biological data, and also provide a more complete understanding of the role of nAChRs in the neurochemical transmission subserving the efferent-afferent interaction in the vestibular periphery.

Animals↗