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Aliasgar V. Moiyadi and Prakash Shetty

OBJECTIVE

Navigated 3D ultrasound is a novel intraoperative imaging adjunct permitting quick real-time updates to facilitate tumor resection. Image quality continues to improve and is currently sufficient to allow use of navigated ultrasound (NUS) as a stand-alone modality for intraoperative guidance without the need for preoperative MRI.

METHODS

The authors retrospectively analyzed cases involving operations performed at their institution in which a 3D ultrasound navigation system was used for control of resection of brain tumors in a “direct” 3D ultrasound mode, without preoperative MRI guidance. The usefulness of the ultrasound and its correlation with postoperative imaging were evaluated.

RESULTS

Ultrasound was used for resection control in 81 cases. In 53 of these 81 cases, at least 1 intermediate scan (range 1–3 intermediate scans) was obtained during the course of the resection, and in 50 of these 53 cases, the result prompted further resection. In the remaining 28 cases, intermediate scans were not performed either because the first ultrasound scan performed after resection was interpreted as showing no residual tumor (n = 18) and resection was terminated or because the surgeon intentionally terminated the resection prematurely due to the infiltrative nature of the tumor and extension of disease into eloquent areas (n = 10) and the final ultrasound scan was interpreted as showing residual disease. In an additional 20 cases, ultrasound navigation was used primarily for localization and not for resection control, making the total number of NUS cases where radical resection was planned 101. Gross-total resection (GTR) was planned in 68 of these 101 cases and cytoreduction in 33. Ultrasound-defined GTR was achieved in 51 (75%) of the cases in which GTR was planned. In the remaining 17, further resection had to be terminated (despite evidence of residual tumor on ultrasound) because of diffuse infiltration or proximity to eloquent areas. Of the 33 cases planned for cytoreduction, NUS guidance facilitated ultrasound-defined GTR in 4 cases. Overall, ultrasound-defined GTR was achieved in 50% of cases (55 of 111). Based on the postoperative imaging (MRI in most cases), GTR was achieved in 58 cases (53%). Final (postresection) ultrasonography was documented in 78 cases. The findings were compared with the postoperative imaging to ascertain concordance in detecting residual tumor. Overall concordance was seen in 64 cases (82.5%), positive concordance was seen in 33 (42.5%), and negative in 31 (40%). Discordance was seen in 14 cases—with ultrasound yielding false-positive results in 7 cases and false-negative results in 7 cases. Postoperative neurological worsening occurred in 15 cases (13.5%), and in most of these cases, it was reversible by the time of discharge.

CONCLUSIONS

The results of this study demonstrate that 3D ultrasound can be effectively used as a stand-alone navigation modality during the resection of brain tumors. The ability to provide repeated, high-quality intraoperative updates is useful for guiding resection. Attention to image acquisition technique and experience can significantly increase the quality of images, thereby improving the overall utility of this modality.

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Aliasgar V. Moiyadi and Prakash Shetty

Object

Repeat surgery for pediatric brain tumors is gaining acceptance, with extent of resection an important predictor of outcome. However, repeat surgeries may be associated with increased morbidity. Few studies in the literature provide such outcomes objectively. The authors report on their experience with repeat surgery at a tertiary care neurooncology referral center in India.

Methods

A prospectively maintained database documented epidemiological, clinical, radiological, operative, and perioperative events. The authors analyzed 117 children (younger than 18 years of age) who had undergone various resective surgeries for brain tumors over a period of 5 years. Assessed end points included immediate postoperative neurological status, neurological outcome at discharge, regional complications, systemic complications, overall morbidity, and mortality.

Results

The majority of children (48%) were between 3 and 10 years of age. Elevated intracranial pressure (70% of patients) and neurological deficits (60% of patients) were the commonest presenting symptoms. A significant proportion of patients (35%) had a poor Karnofsky Performance Scale score (≤ 70). Supratentorial procedures were performed in 58% of the patients. Most patients (72%) had large (> 4 cm) tumors. Fifty-eight patients (50%) had received prior treatment, surgery in 55. Neurological morbidity (worsening), regional complications, and systemic complications occurred in 27%, 32%, and 25% of patients overall, respectively. Overall morbidity was 44.4% (26.5% major), and perioperative mortality was 7.7%. Neurological worsening occurred more frequently in patients undergoing a first surgery (p = 0.038), whereas wound-related complications were more common in those undergoing reoperations (p = 0.00).

Conclusions

Pediatric patients had larger tumors and were more likely to present with a poor performance status, often after prior treatment, than their adult counterparts. Wound-related complications were higher in the previously treated subgroup; however, neurological complications were fewer, probably because of a favorable selection of patients. Despite the unavailability of advanced intraoperative aids, acceptable levels of overall morbidity and mortality could be achieved in repeat surgeries for pediatric brain tumors.