Phillip A. Wackym

Human endolymphatic sac: morphologic evidence of immunologic function

The ultrastructure of ten normal human endolymphatic sacs (ES), fixed immediately after death and obtained at autopsy, was observed by transmission electron microscopy. The roles of the epithelium, subepithelial space, vasculature, and ES leukocytes were morphologically studied to evaluate possible immunologic functions of the human ES. In addition, five intraosseous ES biopsies from patients undergoing translabyrinthine acoustic neuroma resection were studied using the immunoperoxidase technique to identify specific leukocyte subpopulations. Evidence of phagocytic activity included the presence of phagocytic epithelial cells, monocytes, macrophages, and polymorphonuclear leukocytes. Immune surveillance was suggested by intraepithelial and subepithelial T-lymphocytes, numerous fenestrated blood vessels, and the presence of a homogeneously staining substance within the lumina of ES epithelial tubules. No B-lymphocytes were found. The findings support the existence of a local immune system of the normal human inner ear.

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.

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.

Adjunctive use of endoscopy during posterior fossa surgery to treat cranial neuropathies.

OBJECTIVEThe objective of this study was to determine the utility and safety of rigid endoscopy as an adjunct during posterior fossa surgery to treat cranial neuropathies. METHODSA suboccipital craniotomy was performed for 19 patients with non-neoplastic processes involving the Vth, VIIth, and/or VIIIth cranial nerves. Ten patients with trigeminal neuralgia (n = 8), hemifacial spasm (n = 1), or intractable tinnitus (n = 1) underwent primarily microvascular decompression procedures. One patient with geniculate neuralgia underwent nervus intermedius sectioning combined with microvascular decompression. Eight patients underwent unilateral vestibular nerve neurectomies for treatment of Ménière’s disease. A 0- or 30-degree rigid endoscope was used in conjunction with the standard microscopic approach for all procedures. RESULTSAll patients experienced resolution or significant improvement of their preoperative symptoms after posterior fossa surgery. The endoscope allowed improved definition of anatomic neurovascular relationships without the need for significant cerebellar or brainstem retraction. Cleavage planes between the cochlear and vestibular nerves entering the internal auditory canal and sites of vascular compression could not be microscopically observed for several patients; however, endoscopic identification was possible for all patients. There were no complications related to the use of the endoscope. CONCLUSIONThe rigid endoscope can be used safely during posterior fossa surgery to treat cranial neuropathies, and it allows improved observation of the cranial nerves, nerve cleavage planes, and vascular anatomic features without significant cerebellar or brainstem retraction.

Cell and molecular anatomy of nicotinic acetylcholine receptor subunits and calcitonin gene-related peptide in the rat vestibular system.

In this report we demonstrate the pattern of calcitonin gene-related peptide (CGRP) mRNA and immunoreactivity in the central and peripheral vestibular system of the rat, using a CGRP cRNA probe and a polyclonal CGRP antiserum. We present evidence that somata in all regions of efferent vestibular neurons contain CGRP based on the correspondence between in situ hybridization (mRNA) and immunohistochemistry (mRNA translation product). CGRP immunohistochemistry (CGRPi) and in situ hybridization confirm that CGRPi axons and terminals present in the vestibular neuroepithelium are efferent in origin. Immunoelectron microscopy revealed an extensive innervation of the afferent vestibular pathway by CGRPi terminals that was not limited to the primary afferent chalice, as previously reported by Tanaka et al. (Brain Res 1989;504:31–5). An efferent neuromodulator role of CGRP can be inferred from the distribution of terminals found on the primary afferent fibers, and type I and type II hair cells. In addition, we present evidence that nicotinic acetylcholine receptor (nAChR) subunit mRNA is expressed by primary afferent cell bodies. On the basis of these data, a hypothetical molecular mechanism of vestibular efferent modulation of the primary afferent pathway is proposed.In this report we demonstrate the pattern of calcitonin gene-related peptide (CGRP) mRNA and immunoreactivity in the central and peripheral vestibular system of the rat, using a CGRP cRNA probe and a polyclonal CGRP antiserum. We present evidence that somata in all regions of efferent vestibular neurons contain CGRP based on the correspondence between in situ hybridization (mRNA) and immunohistochemistry (mRNA translation product). CGRP immunohistochemistry (CGRPi) and in situ hybridization confirm that CGRPi axons and terminals present in the vestibular neuroepithelium are efferent in origin. Immunoelectron microscopy revealed an extensive innervation of the afferent vestibular pathway by CGRPi terminals that was not limited to the primary afferent chalice, as previously reported by Tanaka et al. (Brain Res 1989;504:31-5). An efferent neuromodulatory role of CGRP can be inferred from the distribution of terminals found on the primary afferent fibers, and type I and type II hair cells. In addition, we present evidence that nicotinic acetylcholine receptor (nAChR) subunit mRNA is expressed by primary afferent cell bodies. On the basis of these data, a hypothetical molecular mechanism of vestibular efferent modulation of the primary afferent pathway is proposed.

Early diagnosis of otologic Wegener's granulomatosis using the serologic marker C-ANCA.

Wegeners granulomatosis is a systemic vasculitis that may involve any organ system. Otologic manifestations are common, and can be the presenting complaint. In the past, diagnosis often necessitated the development of characteristic pulmonary or renal disease. The identification of a new serologic marker, cytoplasmic pattern antineutrophil cytoplasmic autoantibody (C-ANCA), allows for the early diagnosis of Wegeners granulomatosis and gives the patient the best chance for remission with cytotoxic therapy. We report two patients with Wegeners granulomatosis who presented with refractory otitis media, one of whom subsequently developed facial nerve paralysis, in which an early diagnosis was facilitated by the use of the C-ANCA test. Otologic manifestations of Wegeners granulomatosis and the basis of the C-ANCA test are discussed.

Muscle-Flap Coverage of Exposed Endoprostheses

A well-entrenched tenet in the orthopedic community is that dehiscent wounds overlying exposed endoprostheses should be treated by implant removal and delayed reconstruction. A new management protocol utilizing thorough soft-tissue debridement and myocutaneous or muscle-flap coverage was evaluated in four patients at the UCLA Medical Center who presented with exposed endoprostheses. These prostheses were placed for total-joint replacement or limb salvage surgery. All four prostheses and extremities were salvaged without the need for endoprosthesis removal or exchange, and no infections developed. The results suggest that late aseptic wound dehiscence with an exposed endoprosthesis need not be managed with prosthetic removal, arthrodesis, or amputation. This one-stage procedure avoided infection, allowed early mobilization, and shortened hospitalization.

Electrophysiologic Effects of Placing Cochlear Implant Electrodes in a Perimodiolar Position in Young Children

Objective The purpose of this study was to intraoperatively record the electrically evoked auditory brainstem response (EABR) before and after placement of the electrode positioning system (EPS) (CII Bionic Ear with HiFocus I cochlear implant electrode array) as well as before and after stylet removal (Nucleus Contour cochlear implant electrode array). It was hypothesized that physiologic changes would occur after perimodiolar positioning of the electrode array and these changes would be evident from the EABR recordings.

Subdural empyema of otorhinological origin

The UCLA experience with subdural empyema (SDE) of otorhinological origin was reviewed. All cases of SDE with additional intracranial complications were excluded. Thirteen cases of SDE were identified with the predisposing factors being sinusitis (ten), mastoiditis (two), and otitis media (one). Based on data obtained from this review and from studies previously published in the literature, the keys to optimal outcome are rapid diagnosis, craniotomy with complete evacuation of the purulent collection followed by immediate surgical management of the otorhinological source of the SDE, and appropriate antibiotic therapy. Computed tomography is nearly always diagnostic but can be equivocal and magnetic resonance imaging may become the diagnostic study of choice. Of the five patients initially treated with burr holes. None of the patients initially managed with craniotomy were worse or died, whereas of the four patients initially managed with burr holes, two were worse (25 per cent) and two died (25 per cent). Antibiotic therapy is guided by the organisms found in the empyema and the site of origin of the infection. The otolaryngologist must remain aware of the clinical features and management of SDE and work closely with his neurosurgical colleagues to provide early, decisive surgical treatment.

Gamma knife radiosurgery for acoustic neuromas performed by a neurotologist: early experiences and outcomes.

Objective: To assess early outcomes after Gamma knife radiosurgery of acoustic neuromas and other skull base tumors. Background: Gamma knife radiosurgery is one of the available methods to treat acoustic neuromas, in addition to micro-surgical resection. Neurootologists have long been associated with microsurgical resection of these tumors; however, the application of Gamma knife radiosurgery to the treatment of these tumors by neurootologists has not been previously described. Setting: Acoustic Neuroma and Skull Base Surgery Program / Tertiary Referral Center. Study Design/Patients/Intervention: Prospective clinical study of all patients treated by the senior author and our gamma knife team beginning in June 2000. Main Outcome Measures: Preoperative MRI, audiometry, vestibular testing and facial nerve electromyography were completed. At six-month intervals postoperatively, audiometry, caloric testing and MRI were performed to determine thresholds and speech discrimination ability, vestibular function, and the size of the tumor. Results: From June 2000 until March 2004, 38 patients were treated, and these included 33 acoustic neuromas, two meningiomas, one glomus jugulare tumor, and two facial neuromas. Greater than 36 month follow-up was available in 7 patients, > 24 months in 24, > 12 months in 31, and > 6 months in 34 patients. Statistically significant reduction in tumor size was seen over time, and tumor control was achieved in all but two patients. Various patterns of changes in auditory function, both in threshold and speech discrimination were observed in either positive or negative directions. Conclusions: Preliminary experience with Gamma knife radiosurgery indicates that this treatment method represents another option for neurootologists to use in managing patients with skull base tumors.