Accumulation of neurofilament proteins in the regenerating facial nerve.

In order to compare the extent of axonal regeneration in two surgical nerve repair procedures, we measured the levels of the neurofilament (NF) proteins in the regenerating facial nerve of adult New Zealand rabbits. The animals were operated on bilaterally, with a chamber model placed on one side and a cable graft model inserted on the contralateral side. Normal nerve from unoperated animals or nerve removed during nerve repair surgery served as controls. Using immunoblot techniques and densitometric measurement, we examined specific changes in the individual NF [High (H), Medium (M), and Low (L) molecular weight (MW)] in the regenerating nerve at 3 and 7 weeks postoperation time. Linearity of the densitometric system was established by separation of serial dilutions of known NF on the gel, and blotting for immunostaining. The amount of all 3 NF's decreased during the regeneration process compared to normal nerve, but there were differences between the two procedures. The NFH in the distal segment of the chamber repaired nerve at 7 weeks was 60-70% of the preoperative state, which correlated with a previous morphological study of axona) caliber during regeneration. At 3 weeks, NF content was lower in the distal segment of the chamber than in the distal cable graft. By 7 weeks, NF content was similar in proximal and distal segments of both models. Thus, although initial regeneration is slower in the chamber model, the eventual outcome is similar in both chamber and graft.

Computed tomography of orbital medial wall fractures.

Increasing experience with computed tomographic evaluation of head trauma reveals this radiologic modality to be superior to conventional polytomography in the assessment of certain areas of maxillofacial injury. A comparison of hypocycloidal polytomography and computed tomography in nine patients with fractures of the medial wall of the orbit reveals CT to be superior in localization of the fracture site, delineation of displaced bone fragments, and recognition of herniation of intraorbital contents into the ethmoid labyrinth. Information regarding damage to the nasolacrimal duct and associated intraorbital abnormalities such as the presence and location of hemorrhage and foreign bodies is also available from the CT scan.

Localization of ornithine decarboxylase (ODC) in the cochlea of the immature rat.

Ornithine decarboxylase (ODC), the rate-limiting enzyme in polyamine synthesis, is important in cochlear development. Whereas tissue specific differences in cochlear ODC activity have been demonstrated, cellular localization of ODC protein in the inner ear of the immature rat has not. ODC was localized in inner ear structures using an ODC polyclonal antibody and the effects of cycloheximide on ODC immunoreactivity and enzymatic activity were determined. Tissues demonstrating elevated enzymatic activity contained cells with the strong immunoreactivity. ODC activity was highest in the organ of Corti and lateral wall followed by the cochlear nerve. Immunoreactivity was demonstrated throughout the cochlea with intense staining of the hair cells, pillar cells, Deiter's cells, inner sulcus cells, basilar membrane, stria vascularis, spiral ganglion cell bodies and cochlear nerve fibers. Cycloheximide rapidly diminished cochlear ODC activity and expression of ODC protein. The half-life of cochlear ODC was 30 min. Localization of cellular sites of ODC is important in understanding the role of the ODC-polyamine pathway in cochlear development and will be a valuable marker for tissue damage from ototoxic agents.

Facial electroneurography: analysis of techniques and correlation with degenerating motoneurons.

Facial electroneurography is the one electrophysiologic test that quantifies the degree of nerve degeneration. This two-part study establishes electroneurography (ENoG) as a reliable and valid system of measurement. Part I examines three different ENoG techniques in normal subjects and in patients with advanced paralysis. Myogenic compound action potential (CAP) absolute amplitudes differ according to methodology, site, and gender. Analyses of side-to-side and test-retest CAP differences demonstrate optimized and standardized recording lead techniques to be comparable and consistent when CAPs are recorded in the midface. The most significant variable is time, i.e., the inconsistency of test-retest results. The coefficient of reliability increases when averaging results of test sessions repeated at a similar point in time. Part II, an animal model, supports the correlation between ENoG predictions following facial nerve injury and the level of motoneuron degeneration, as assessed by retrograde transport of horse-radish peroxidase to the somata of the facial motor nucleus and by peripheral axon counts.

Histologic correlation of the degenerating facial nerve with electroneurography.

The myogenic compound action potential (CAP) measured by electroneurography (EnoG) is hypothesized to correlate directly with the number of viable motoneurons in the facial nerve. In an animal model (cat), two independent ENoG techniques, standardized recording lead placement (SRLP) and optimized recording lead placement (ORLP), were used to record CAPs evoked from nerves undergoing degeneration. Normal test-retest variability simulated human studies. Peripheral counts of viable axons correlated with N1 amplitude (ORLP ENoG), peak-to-peak (absolute) amplitude (both ENoG techniques), and area under the negative phase of the diphasic CAP waveform (both ENoG techniques) recorded over the whisker pad. These results validate ENoG as a reliable indicator of neural integrity following traumatic lesions of the facial nerve.

Histopathology of temporal bone fractures: implications for cochlear implantation.

Temporal bone fractures often cause loss of audiovestibular function. Those patients with bilateral profound sensorineural hearing losses secondary to temporal bone fractures become candidates for cochlear implantation. The authors present the histopathology of five temporal bone fractures in three patients, evaluating specifically the traumatic effects on the neural elements of the inner ear. Transverse fractures of the temporal bone result in severe loss of hair cells, ganglion cells, and other supporting cells in the inner ear. Occasionally labyrinthitis ossificans may occur as a consequence of trauma or infection. While longitudinal fractures do not violate the otic capsule, these same neural elements may be damaged by concussion.

Velo-pharyngo-laryngeal myoclonus: evaluation of objective tinnitus and extrathoracic airway obstruction.

Velo-pharyngo-laryngeal myoclonus, the rapid, rhythmic contraction of muscles of the pharynx and larynx, is a rare neurological manifestation of numerous disease processes affecting the cerebellum. In its most common form, palatal myoclonus, this disease frequently presents to the otolaryngologist as objective tinnitus. Impedance audiometry provides a useful means of verifying suspected palatal myoclonic activity through recorded changes in the middle ear pressure, as mediated by muscle activity at the proximal portion of the eustachian tube. A very rare case of velo-pharyngo-laryngeal myoclonic with clonic contraction of the laryngeal adductors and subsequent extrathoracic airway obstruction is presented. Tracheostomy provided immediate symptomatic relief of dyspnea.

Cost-effectiveness of the diagnostic evaluation of vertigo.

OBJECTIVE: To evaluate the cost-effectiveness of several diagnostic tests used in the evaluation of vertigo. STUDY DESIGN: Cost-effectiveness analysis, using data from retrospective case review. METHODS: Charts and test results were reviewed from 192 outpatients seen in an academic tertiary referral center for evaluation of vertigo. Cost-effectiveness analysis was performed using decision analysis software, data from office and hospital charges, and expert-based estimations of the utility of different test outcomes. Sensitivity analysis was performed using standard algorithms and wide variable ranges. RESULTS: We found that audiologic testing, posturography, and electronystagmography were the most cost-effective tests, and that magnetic resonance imaging and blood tests had the lowest cost-effectiveness. The analysis was sensitive to the effects of financial costs of tests but, with a few exceptions, was typically not sensitive to the utility of test outcomes or the distribution of test results. CONCLUSIONS: The use of cost-effectiveness analysis, the estimation of utility of test outcomes, and techniques of sensitivity analysis should help guide the clinician's decision making on appropriate testing for patients with vertigo.

Nontuberculous mycobacterial infections of the head and neck.

OBJECTIVE: To review the treatment and outcome of patients with nontuberculous mycobacterial infections of the head and neck. DESIGN: Retrospective examination of the medical records of patients treated by several surgeons during a 5-year period with a minimum 6-month follow-up. SETTING: Large teaching children's hospital. PATIENTS: Twenty-six children hospitalized for treatment of nontuberculous mycobacterial infections of the head and neck. MAIN OUTCOME MEASURES: Resolution of infection, recurrence, and need for additional surgical intervention for cure. RESULTS: Eleven patients initially were treated by incisional biopsy or incision and drainage procedures; eight patients developed recurrence or a draining sinus tract, necessitating a second surgical procedure. In contrast, 15 patients initially underwent complete excision; only one developed a recurrence (P < .01). Thus, eight (31%) of 26 patients required at least two surgical procedures owing to inadequate initial treatment. CONCLUSIONS: Excisional biopsy is both the diagnostic procedure and treatment of choice for nontuberculous mycobacterial adenitis.

Migraine and sudden sensorineural hearing loss.

A 62-year-old woman developed recurrent episodes of sudden sensorineural hearing loss, occurring with migraine headaches. This is an unusual complication of migraine, which probably arises from a reversible vasoconstriction of the cochlear blood vessels. Pathogenesis of migraine and its variants are reviewed herein, along with the rationale of the modalities in its treatment. In this case, the patient's hearing improved after administration of ergot alkaloids, carbon dioxide/oxygen inhalations, and stellate ganglion blocks; it is not known whether this improvement represented therapeutic effect or spontaneous recovery.

Intradiploic epidermoid cyst of the sphenoid wing.

Epidermoids are blastomatous malformations of abnormal epithelial proliferation. Intradiploic epidermoids are very rare lesions that may occur in all flat bones of the calvarium and in the paranasal sinuses, maxilla, temporal bone, and sphenoid bone. This article describes the unique case of an intradiploic epidermoid tumor located in the greater sphenoid wing. Theories of pathogenesis, clinical behavior, diagnosis, and treatment of diploic epidermoids are reviewed.

Surgical dimensions of the facial recess in adults and children.

The facial recess approach permits surgical access to the round window area. This route is used in patients who are undergoing cochlear implantation. To evaluate the feasibility of this procedure in children as compared with adults, serial sections of temporal bones were used to measure the surgical dimensions of the facial recess. No statistically significant differences in the dimensions of the facial recess or the extended facial recess approaches were found between children and adults. The relationship of the facial and chorda tympani nerves to the annular plane exhibited no change with postnatal growth. These structures translate posteriorly and laterally toward the annular plane as they descend within the temporal bone. Therefore, the facial recess approach represents no greater hazard in a child than in an adult.

Hereditary congenital cholesteatoma. A variant of branchio-oto dysplasia.

A mother and daughter both presented at age 5 years with the triad of right-sided congenital cholesteatoma, right preauricular pits, and bilateral sensorineural hearing loss. Twenty-six years apart, both were treated with middle ear exploration and removal of a cholesteatoma that filled the sinus tympani, facial recess, and middle ear. The sensorineural hearing losses were nonprogressive, and the preauricular pits were asymptomatic. These two cases may represent a unique variant of branchio-oto dysplasia. The mechanism of formation of these anomalies and the possible modes of inheritance are conjectural. This triad, however, supports genetic predisposition rather than aberrant epithelial rests during morphogenesis as a possible cause in congenital cholesteatoma.

Facial paralysis as the initial presentation of an internal carotid artery aneurysm.

Aneurysms of the intrapetrous internal carotid artery are rarely encountered and can present difficult diagnostic problems. A review of the literature revealed 34 cases, and we now add a 35th. Presenting symptoms and signs are dependent on the direction of expansion of the aneurysm, with neurologic dysfunction typical of medial expansion, whereas lateral erosion often suggests a glomus tumor.

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.

Stimulation variables in electroneurography of the facial nerve.

Electroneurography is an electrophysiologic measurement of compound action potentials elicited by the supramaximal stimulation of a peripheral nerve. The stimulus intensity-response function was examined in the cat facial nerve following stimulation over two different sites of the facial nerve: the main trunk and the buccal branches. Thresholds were achieved at lower current settings, the resultant compound action potential exhibited a greater amplitude, and masseter muscle excitation was more evident following stimulation over the buccal region. The use of concurrent facial- and masseter-evoked electromyographic monitoring allows more sensitive detection of masseter excitation and a more accurate determination of the current level necessary for supramaximal stimulation.

Sudden sensorineural hearing loss as a presentation of multiple sclerosis.

While auditory involvement in multiple sclerosis is not infrequent, sensorineural hearing loss as the initial manifestation of this disease is rare. Auditory brain-stem evoked responses, speech audiometry, acoustic reflexes, and electronystagmography yield significant objective information concerning brain-stem involvement. Magnetic resonance imaging objectively documents white matter demyelinization. The acute onset of the retrocochlear type of auditory dysfunction without other evidence of central nervous system involvement can be an early manifestation of this disease. Two patients with multiple sclerosis had sudden sensorineural hearing loss, with one patient experiencing this as the sole initial complaint.

Nontuberculous mycobacterial mastoiditis.

Although nontuberculous mycobacterial (NTM) infections are recognized as an important cause of cervicofacial lymphadenopathy in children, NTM mastoiditis is rare. Further, NTM mastoiditis may be difficult to distinguish clinically from tuberculous mastoiditis since both may present with chronic, painless otorrhea and exuberant middle ear granulation tissue. The treatment of tuberculous mastoiditis is antituberculosis chemotherapy; however, most NTM infections are resistant to antituberculous agents, and the preferred treatment of NTM mastoiditis is mastoidectomy. We report a recent case of mastoiditis caused by Mycobacterium avium complex in an infant who presented with a temporal bone mass.

Progressive hearing loss after transverse temporal bone fracture.

Transverse fractures often violate the otic capsule and commonly, although not invariably, result in immediate and profound sensorineural hearing loss. The pathogenic mechanisms producing sensorineural hearing loss include direct trauma to the cochlear nerve, disruption of the membranous labyrinth, vascular compromise or hemorrhage into the inner ear, perilymphatic fistula, and endolymphatic hydrops. The last two mechanisms account for the occasional patient who develops progressive sensorineural hearing loss after the initial insult. On early posttraumatic evaluation three patients were discovered to have transverse fractures and residual auditory function. Deterioration of hearing led to middle-ear exploration with closure of perilymphatic fistulas. Hearing was preserved in two patients. Diagnosis of posttraumatic perilymphatic fistulas requires early audiometric assessment, high-resolution computed tomographic scanning of the temporal bones to detect fracture of the otic capsule and pneumolabyrinth, and a high index of clinical suspicion.

A comparative study of the fallopian canal at the meatal foramen and labyrinthine segment in young children and adults.

If entrapment is a critical factor in pathogenesis, the lower incidence of Bell's palsy in children compared with adults may have an anatomical basis. Histologic sections of 20 temporal bones from children younger than 2 years were examined to determine the diameter of the facial nerve and fallopian canal at the meatal foramen and in the labyrinthine segment. No statistically significant difference in the nerve/canal ratios in these areas was found. Comparisons were made with similar data from 10 adult temporal bones. The nerve/canal ratios in the labyrinthine portion were similar in both age groups; however, the ratio at the meatal foramen was significantly smaller in children. This may be due, in part, to growth of the vertical crest, which was found to increase considerably in length and width by adulthood. These results suggest that the facial nerve is not as tightly contained at the meatal foramen in children and provides a possible explanation for the relative infrequency of Bell's palsy in this age group.