Are Acoustic Neuromas Encapsulated Tumors?

Recurrences and progression following microsurgery of vestibular schwannoma

Background

The treatment approach of vestibular schwannoma (VS) has seen a change in recent years, with a trend away from radical surgery towards preservation of cranial nerve function. A recent study reported recurrences as long as 20 years after complete removal of VS.

Objective

To report the risk of recurrence and progression in our patient population the authors retrospectively reviewed outcomes of patients.

Methods

Cases with unilateral VS who had undergone primary microsurgery via retrosigmoidal approach between 1995 and 2021 were investigated. Complete tumor removal was defined as gross total resection (GTR), a capsular remnant was categorized as near total resection (NTR) and residual tumor was designated as subtotal resection (STR). The primary endpoint was radiological recurrence-free survival.

Results

386 patients fulfilled the inclusion criteria of the study and were evaluated. GTR was achieved in 284 patients (73.6%), NTR was achieved in 63 patients (10.1%) and STR was present in 39 patients (16.3%). A total of 28 patients experienced recurrences with significant differences in the three subgroups. The strongest predictor of recurrence was the extent of resection, with patients who underwent STR having an almost 10-fold higher risk of recurrence and patients who had undergone NTR having an almost 3-fold higher risk than those treated with GTR. More than 20% of recurrences (6/28) occured after more than 5 years.

Conclusion

The degree of resection is an important guide to the interval of follow-up, but long-term follow-up should be considered also in the case of GTR. The majority of recurrences occurs after 3-5 years. Nevertheless, a follow-up of at least 10 years should be carried out.

Description of the Diversity in Surgical Indication and Surgical Strategies for Primary Spinal Cord Tumors: A Nationwide Survey by the Neurospinal Society of Japan

OBJECTIVE

To assess the current management of primary spinal cord tumors (PSCTs) and determine whether and to what extent there are differences in surgical strategies for PSCTs.

METHODS

The Neurospinal Society of Japan conducted a survey between April 1 and 30, 2021. Certified spine surgeons were requested for information on the frequency of surgeries in 2020 and the surgical strategies adopted for each PSCTs. The following tumor histologies were focused: schwannoma, meningioma, and cauda equina tumor as extramedullary tumors; and ependymoma, hemangioblastoma, astrocytoma, and cavernoma as intramedullary tumors. The participants were divided according to their response as follows: experts, who had experienced ≥ 100 surgeries for PSCTs, and nonexperts.

RESULTS

Among 308 participants (63%), 35 (11%) were experts. The total number of PSCTs in 2020 was 802 of which 564 tumors were extramedullary and 223 were intramedullary. Schwannoma accounted for 53% of the extramedullary tumors, and ependymoma accounted for 39% of the intramedullary tumors. Surgical strategies significantly differed among both the experts and nonexperts groups. Some discrepancies in the adopted surgical strategies were observed between groups. Some of the nonexperts, and none of the experts, ruled out surgery for schwannomas (Eden type 4), astrocytomas, or cavernomas. Five nonexperts (2.2%), and none of the experts, resected the entire dura for meningiomas.

CONCLUSION

A nationwide survey revealed that a sufficient consensus did not exist regarding surgical strategies for PSCTs. A disease-specific registry for PSCTs is necessary in academic societies.

The fate of the tumor remnant after less-than-complete acoustic neuroma resection

OBJECTIVES

We sought to determine the recurrence rate after near-total and subtotal resection of acoustic neuroma.

STUDY DESIGN, SETTING, AND PATIENTS

We conducted a retrospective chart review of a total of 79 patients: 50 with near-total resections (remnant < or =25 mm(2) and < or =2 mm thick) and 29 with subtotal resections (any larger remnant). Surgical approach included 5 middle fossa, 17 retrosigmoid, and 57 translabyrinthine.

MAIN OUTCOME MEASURES

Recurrence was defined as documented tumor growth by serial imaging or the recommendation for further treatment after a single scan. No recurrence was defined as no visible tumor on imaging for a minimum follow-up time of 3 years or tumor remnants that remained unchanged on serial scans (mean, 5-year follow-up).

RESULTS

Fifty-two patients were included in the study group. Recurrences were seen in 1 (3%) of 33 patients who had a near-total resection compared with 6 (32%) of 19 patients who had a subtotal resection. After adjustment for follow-up time and large tumor size, the odds ratio for recurrence was 12 times larger for subtotal than for near-total resections (P = 0.033). All recurrences were seen following the translabyrinthine approach in the mid-cerebellopontine angle. None were encountered in the internal auditory canal. The mean time interval from surgery to the detection of a recurrence was 3 years (range, 1 to 5 years).

CONCLUSIONS

The recurrence rate when performing a near-total resection is low but is substantially higher with a subtotal resection. Recurrences can be detected within the first 5 postoperative years. We recommend near-total resection in any patient if needed to preserve neural integrity. Subtotal resection is best avoided whenever possible; however, adjunctive treatment with stereotactic radiotherapy may be considered.