Increased local recurrence in advanced parotid malignancy treated with mastoidectomy without lateral temporal bone resection

OBJECTIVE

We analyzed patients with advanced parotid malignancy requiring proximal facial nerve exposure undergoing mastoidectomy versus lateral temporal bone resection to determine differences in local and distant recurrence.

STUDY DESIGN

The study design is a case series with chart review.

SETTING

The setting is in Tertiary care practice in Fort Worth, Texas from January1998 to January 2014.

SUBJECTS AND METHODS

The study included 120 patients with advanced parotid malignancy, 82 males between 19 and 87 years, and 38 females between 26 and 83 years. Patients with no overt bone involvement were treated with parotidectomy and mastoidectomy for exposure of the proximal facial nerve, and patients with clinically suspected (radiographic imaging or clinical fixation) bone involvement were treated with parotidectomy and lateral temporal bone resection. Follow up ranged from a minimum of 18 months to 11 years following surgery.

RESULTS

Sixty patients were treated with mastoidectomy and 60 were treated with lateral temporal bone resection. In patients treated with mastoidectomy, 13 had local recurrence and 7 had distal recurrence. In patients treated with lateral temporal bone resection, 2 had local recurrence while 9 had distant recurrence. Statistical analysis revealed that patients treated with mastoidectomy developed local recurrence (p = 0.0022) more commonly than those treated with lateral temporal bone resection. There was no significant difference in distant recurrence between both groups (p = 0.5949).

CONCLUSIONS

Patients with advanced parotid malignancy should be treated aggressively with parotidectomy and lateral temporal bone resection regardless of bone involvement due to increased risk of local recurrence in those treated with mastoidectomy alone.

LEVEL OF EVIDENCE

Level of evidence is a 4 case series.

Hearing loss in children with very low birth weight: current review of epidemiology and pathophysiology

An association between birth weight <1500 g (very low birth weight (VLBW)) and hearing loss has been long recognised. As universal hearing screening programmes have become widely implemented and the survival rate of VLBW babies in modern intensive care units has increased, we have gained a substantially better understanding of the nature of this problem. However, many gaps in our knowledge base exist. This review describes recent data on hearing loss in the VLBW population and explains the current level of understanding about the physiological basis underlying the auditory deficits in these patients. Although VLBW alone may not have a severe impact on hearing, it is commonly associated with multiple other risk factors that can alter hearing in a synergistic fashion. Therefore, the risk of hearing loss is substantially higher than in the general newborn population. Also, it is important to perform a more comprehensive audiometric evaluation than standard otoacoustic emission screening for infants who are in the neonatal intensive care unit in order not to miss hearing loss due to retrocochlear pathology. Furthermore, children with VLBW are also at increased risk of experiencing progressive or delayed-onset hearing loss, and thus should continue to have serial hearing evaluations after discharge from the neonatal intensive care unit.

Peripetrosal arachnoid cysts

PURPOSE OF REVIEW

The present review summarizes the current theories on arachnoid cyst formation, the common presentations of cysts surrounding or eroding the temporal bone from the middle and posterior cranial fossae, the diagnostic strategies and the management considerations and options.

RECENT FINDINGS

Arachnoid cysts are most common in the middle cranial fossa and rarely present in association with the petrous apex. They are frequently found incidentally on imaging studies performed in the workup for unrelated symptoms. When they do cause symptoms, these are usually nonspecific. Thus it is important to establish the relationship between the two. Peripetrosal arachnoid cysts may cause cranial nerve deficits in addition to symptoms related to intracranial hypertension. Small asymptomatic cysts are managed conservatively with serial imaging. Large symptomatic cysts are often managed surgically with shunting, open excision or open or neuroendoscopic fenestration or marsupialization. The management of large asymptomatic cysts depends on the patient and cyst characteristics.

SUMMARY

Peripetrosal arachnoid cysts are often incidental findings. Careful selection of surgical candidates is of utmost importance. Multiple surgical options with similar success rates are available. The rates and profile of their complications may differ. Overall, approximately 70% of patients experience improvement in their symptoms with surgery.

Assessment of differential gene expression in vestibular epithelial cell types using microarray analysis

Current global gene expression techniques allow the evaluation and comparison of the expression of thousands of genes in a single experiment, providing a tremendous amount of information. However, the data generated by these techniques are context-dependent, and minor differences in the individual biological samples, methodologies for RNA acquisition, amplification, hybridization protocol and gene chip preparation, as well as hardware and analysis software, lead to poor correlation between the results. One of the significant difficulties presently faced is the standardization of the protocols for the meaningful comparison of results. In the inner ear, the acquisition of RNA from individual cell populations remains a challenge due to the high density of the different cell types and the paucity of tissue. Consequently, laser capture microdissection was used to selectively collect individual cells and regions of cells from cristae ampullares followed by extraction of total RNA and amplification to amounts sufficient for high throughput analysis. To demonstrate hair cell-specific gene expression, myosin VIIA, calmodulin and alpha9 nicotinic acetylcholine receptor subunit mRNAs were amplified using reverse transcription-polymerase chain reaction (RT-PCR). To demonstrate supporting cell-specific gene expression, cyclin-dependent kinase inhibitor p27kip1 mRNA was amplified using RT-PCR. Subsequent experiments with alpha9 RT-PCR demonstrated phenotypic differences between type I and type II hair cells, with expression only in type II hair cells. Using the laser capture microdissection technique, microarray expression profiling demonstrated 408 genes with more than a five-fold difference in expression between the hair cells and supporting cells, of these 175 were well annotated. There were 97 annotated genes with greater than a five-fold expression difference in the hair cells relative to the supporting cells, and 78 annotated genes with greater than a five-fold expression difference in the supporting cells relative to the hair cells.

Selective acquisition of individual cell types in the vestibular periphery for molecular biology studies

OBJECTIVES

To develop a method for characterizing the transcriptome of individual cell types in the inner ear sensory epithelia.

STUDY DESIGN

We employed the technique of laser capture microdissection to obtain enriched populations of hair cells and supporting cells. The respective mRNAs were extracted, reverse transcribed, and amplified using PCR.

RESULTS

We were able to isolate RNAs with good integrity from enriched cell populations obtained with laser capture microscopy and amplify specific mRNA targets.

CONCLUSIONS

We can now investigate the molecular differences between the different cell types in the inner ear sensory epithelia as identified by morphological criteria.

SIGNIFICANCE

Analysis of gene expression profiles in the inner ear cell types has been hampered by the small size of this tissue and by the compact histoarchitecture of the sensory epithelia; however, the present technique offers new possibilities for the analysis of transcriptomes in the vestibular periphery using available high-throughput gene expression analysis methods.

Fungal biofilm formation on cochlear implant hardware after antibiotic-induced fungal overgrowth within the middle ear

Cochlear implantation in patients with chronic suppurative otitis media is managed with perioperative antibiotics; however, fungal overgrowth can occur. We present a child who received oral cefdinir and topical ofloxacin (Floxin). After 6 weeks, a fungal (Candida) biofilm was demonstrated on the implant surface. In this clinical setting, an antimicrobial strategy using an oral antifungal to prevent fungal overgrowth is a possibility.

Expression and distribution of μ opioid receptors in the inner ear of the rat

Opioid peptides have demonstrated modulatory effects on the vestibular afferent discharge and are putative vestibular efferent neuromodulators. The distribution of their receptors in the mammalian vestibular epithelia is not known. We used reverse transcriptase-polymerase chain reaction (RT-PCR), in situ hybridization, Western blots and immunohistochemistry to study the expression of mu opioid receptor (MOR) in the Scarpa's ganglia and cristae ampullares of rats. MOR transcript was only detected in the somata of the vestibular afferent neurons. MOR-like immunoreactivity was observed in the somata of vestibular afferents and in nerve terminals in the cristae ampullares epithelia both in the center and peripheral regions. Double labeling of cristae sections with the MOR1 antibody in combination with antibodies against calretinin (a marker for vestibular afferents terminating in calices) and peripherin (a marker for afferents terminating in boutons), respectively showed that MOR1 immunoreactivity was in calyx, dimorphic and bouton vestibular afferents. MOR immunoreactivity was not detected in vestibular efferent fibers identified with choline acetyltransferase immunohistochemistry. These results indicate that MOR may mediate effects of vestibular efferents on afferents.

In vivo and in vitro localization of brain-derived neurotrophic factor, fibroblast growth factor-2 and their receptors in the bullfrog vestibular end organs

The inner ear sensory epithelia of vertebrates are composed mainly of supporting cells and hair cells (HCs). Brain-derived neurotrophic factor (BDNF) and fibroblast growth factor-2 (FGF-2) are trophins that are believed to play an essential role in the development and innervation of inner ear epithelia. Both trophins also may play a crucial role in the maintenance and regeneration of hair cells in the adult vertebrate ear. In the bullfrog vestibular system, hair cells are produced throughout life, and the epithelia regenerates following ototoxicity. The expression of BDNF and FGF-2 in the vestibular organs of the adult bullfrog was investigated at a cellular level both in histological sections and in vitro in dissociated cell cultures. In histological sections of the crista ampullaris, in situ hybridization and immunocytochemical techniques demonstrated that HCs express both BDNF and its receptor trkB, while the supporting cells express the receptor trkB alone. Following dissociation and in vitro cell culture no changes in the pattern of BDNF and trkB receptor were observed. Immunocytochemical studies demonstrated that in vivo hair cells express FGF-2 and the receptors FGFR-1 and FGFR-2 while supporting cells do not express either molecule. Following dissociation, HCs continue to express FGF-2 and its two receptors, while supporting cells upregulate the expression of FGF-2 and its receptor FGFR-2. These data confirm the potential role of BDNF and FGF-2 trophic regulation of the sensory epithelia of the adult inner ear. The findings suggest that BDNF has a role in the maintenance of the vestibular epithelia while FGF-2 may regulate the proliferation of supporting cells.

Hair cell formation in cultures of dissociated cells from the vestibular sensory epithelium of the bullfrog

HYPOTHESIS

Bullfrog vestibular hair cells are capable of regenerating in vitro.

BACKGROUND

Recent studies have established that sensory organs in the inner ear of vertebrates continue to produce hair cells after birth. However, the mechanisms responsible for the regulation of this process are not well understood. The current study reports the development of a novel method for the culture of dispersed cells from the bullfrog inner ear.

METHODS

New hair cell formation in this in vitro preparation was shown by sequential photomicroscopy. Studies with the selective marker for mitotic activity 5-bromo-2-deoxyuridine (BrdU) were done to estimate the level of cell proliferation and to quantify postmitotic hair cell formation. Finally, confirmation of cell type was obtained by scanning electron microscopy and by the use of specific markers for hair cells.

RESULTS

Once the optimal culture conditions were established in the initial experiments, the formation of new hair cells was directly visualized in all unstained live cultures and fixed preparations without exception. Asymmetric division of progenitor cells, with subsequent differentiation of one of the daughter cells into new hair cells, also was documented by photomicroscopy. Approximately 12% of the cells were labeled with BrdU, of which 6% were hair cells, showing that new hair cell formation was subsequent to mitotic division in vitro. The identity of newly formed hair cells was verified as follows: 1) morphologically by scanning electron microscopy; 2) by positive labeling with phalloidin-rhodamine, a marker for actin; and 3) by positive calmodulin immunocytochemistry.

CONCLUSIONS

This study reports the development of an in vitro culture preparation in which undifferentiated epithelial cells proliferate to become new hair cells. Evidence is provided of division of hair cell progenitors and subsequent differentiation of the daughter cells as one of the mechanisms involved in new hair cell formation in the culture preparation. This newly developed cell culture technique provides a powerful tool for further study of the process of hair cell formation in the vestibular end organ.