Histological characteristics of intra-temporal facial nerve paralysis in temporal bone malignancies

The Role of Temporal Bone Pneumatization on Fracture Line and Involved Cranial Structures

OBJECTIVE

Temporal bone pneumatization (TBP) is speculated to serve as a shock absorber in temporal bone fractures (TBF), directing the fracture line away from vital structures. This study correlates TBP extent with TBF patterns and preservations of vital TB structures.

STUDY DESIGN

Retrospective cohort study.

SETTING

Tertiary referral medical center.

METHODS

All TBF patients referred to a single tertiary center 2017 to 2023 were evaluated. A pneumatization index score for each of their TBs was derived by counting automated-voxel density in a 0 to 100 scale. Results were correlated to the TBF type and the violated structure(s). The ossification index was compared to previously detailed qualitative classification systems of TBP.

RESULTS

One hundred and forty-five patients were enrolled (mean age 43 ± 17 years). Kinematics were motor vehicle accidents (46%), scooter (15%), bicycle (14%), falls (13%), and assaults (8%). The mastoid ossification index we used showed a strong correlation to all qualitative classification systems (sigmoid = 0.829; labyrinthine = 0.849; carotis = 0.863, infralabyrinthine = 0.869, all P < .001). The pneumatization index strongly correlated with capsule-violating TBFs, with a mean of 44 ± 23 for otic capsule-sparing TBF and 61 ± 20 for otic capsule-violating (OCV) TBF (P < .001). The facial nerve was violated in 30 patients. Facial canal (FC) involvement was not correlated to the ossification index: it was 49 ± 23 for FC-sparing and 44 ± 23 for FC-violating (P = .620).

CONCLUSION

TBP serves as a protective mechanism against OCV TBF. The more pneumatized the TB, the less likely the otic capsule will be violated in the event of a TBF with the exception of the carotid and FCs. TBP index is in strong agreement with qualitative TBP classification systems.

The Ansa Hypoglossi: Quantifying Axonal Density of a Donor Nerve for Facial Reinnervation

Background: There are a number of nerve grafting options for facial reanimation and the ansa hypoglossi (AH) may be considered in select situations. Objective: To compare axonal density, area, and diameter of AH with other nerves more usually used for facial reanimation. Methods: AH specimens from patients undergoing neck dissections were submitted in formalin. Proximal to distal cross sections, nerve diameters, and the number of axons per nerve, proximally and distally, were measured and counted. Results: Eighteen nerve specimens were analyzed. The average manual axon count for the distal and proximal nerve sections was 1378 ± 333 and 1506 ± 306, respectively. The average QuPath counts for the proximal and distal nerve sections were 1381 ± 325 and 1470 ± 334, respectively. The mean nerve area of the proximal and distal nerve sections was 0.206 ± 0.01 and 0.22 ± 0.064 mm2, respectively. The mean nerve diameter for the proximal and distal nerve sections were 0.498 ± 0.121 and 0.526 ± 0.75 mm, respectively. Conclusion: The histological characteristics of the AH support clinical examination of outcomes as a promising option in facial reanimation.

Treatment of advanced squamous cell carcinoma of the external auditory canal: Critical analysis of persistent failures in diagnosis and surgery with a competing-risk model

BACKGROUND

A series of temporal bone squamous cell carcinomas (TBSCCs) was analyzed with the aim of (i) better understanding the causes for the persistent high failure rate in advanced SCCs and (ii) discussing a possible way out from this stalemate in treatment.

METHODS

Forty-five TBSCCs consecutively treated surgically were reviewed.

RESULTS

The 5-year cumulative incidence for postoperative local recurrence was 41.8%. At multivariable analysis, pT3-4 stages were associated with eightfold relative incidence of developing local recurrence during follow-up (sHR = 9.06, 95% confidence interval [CI] = 1.18-69.46, p = 0.034) and cause-specific death (sHR = 7.95, 95%CI = 1.01-62.27, p = 0.048).

CONCLUSIONS

The poor outcome in advanced TBSCC occurred because of local recurrence due to defective resection. The fundamental pitfall of surgery on advanced TBSCC appeared to be the insufficient knowledge of microscopic tumor growth in the different sites and subsites of the temporal bone. The serial histopathological study of the en bloc surgical specimen and autopsy temporal bones seems to represent a way to enhance our understanding of these tumors.

Solitary breast cancer metastasis to the facial nerve

Facial nerve (FN) palsy, as a solitary symptom, resulting from metastatic tumor is not frequent. In this article, we report an unusual case of the breast cancer metastasis to the labyrinthine segment of a facial nerve.

The Experience of a Facial Nerve Unit in the Treatment of Patients With Facial Paralysis Following Skull Base Surgery

: The management of facial paralysis following skull base surgery is complex and requires multidisciplinary intervention. This review shows the experience of a facial nerve (FN) unit in a tertiary university referral center. A multidisciplinary approach has led to the breaking of some old treatment paradigms. An overview of five FN scenarios is presented. For each setting a contemporary approach is proposed in contrast to the established approach. 1) For patients with an anatomically preserved FN with no electrical response at the end of surgery for vestibular schwannoma, watchful waiting is usually advocated. In these cases, reinforcement with an interposed nerve graft is recommended. 2) In cases of epineural FN repair, with or without grafting, and a poor expected prognosis, an additional masseter-to-facial transfer is recommended. 3) FN transfer, mainly hypoglossal-to-facial and masseter-to facial, are usually chosen based on the surgeons' preference. The choice should be based on clinical factors. A combination of techniques improves the outcome in selected patients. 4) FN reconstruction following malignant tumors requires a combination of parotid and temporal bone surgery, involving different specialists. This collaboration is not always consistent. Exposure of the mastoid FN is recommended for lesions involving the stylomastoid foramen, as well as intraoperative FN reconstruction. 5) In patients with incomplete facial paralysis and a skull base tumor requiring additional surgery, consider an alternative reinnervation procedure, "take the FN out of the equation" before tumor resection. In summary, to achieve the best results in complex cases of facial paralysis, a multidisciplinary approach is recommended.

Invasion Patterns of External Auditory Canal Squamous Cell Carcinoma: A Histopathology Study

OBJECTIVES/HYPOTHESIS

To describe the histopathology of the invasion patterns of advanced-stage external auditory canal (EAC) squamous cell carcinoma (SCC). Study Design Retrospective cohort study.

METHODS

Retrospective analysis of medical records of patients diagnosed with EAC SCC available at the Massachusetts Eye and Ear temporal bone (TB) collection. TBs underwent processing for histologic examination. Hematoxylin and eosin-stained slides were examined. Histologic findings were compared to premortem clinical data.

RESULTS

Nine TBs were identified. Male:female ratio was 6:3. The average age of diagnosis and duration of survival was 64 (46-80 years) and 2.3 years (1-50 months), respectively. All presented with T4 disease, most commonly due to petrous apex (PA) invasion and facial nerve (FN) weakness. The mastoid air cells system served as a tumor conduit to the tegmen mastoideum and overlying dura in four patients, posterior fossa dura in one patient, vertical segment of FN in four patients, and middle ear (ME) and lateral semicircular canal in five patients. The tumor did not penetrate the tympanic membrane, oval window membrane (fenestra vestibule), or round window (RW) membrane. Supra- and infralabyrinthine pneumatization patterns allowed direct routes to the PA. Translabyrinthine PA invasion was seen in two patients. The most common locus of otic capsule invasion was the cochlea. One patient had FN paralysis due to compression rather than invasion.

CONCLUSIONS

SCC does not tend to extend from the ME to the inner ear through the RW and vestibule-stapedial ligament. Tumors tend to spread along the preexisting TB air-tract routes. Well-aerated TB, may facilitate extension to the PA.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E590-E597, 2021.