The stereotactic approach to brain stem lesions: a follow-up of 29 cases

Pediatric Brainstem Tumor Biopsy: Surgical Planning and Execution for Maximal Safety and Tissue Yield

Brainstem tumors account for 10-20% of pediatric brain tumors with a peak age of diagnosis between 7 and 9 years old and are often fatal. Historically, diagnosis of brainstem tumors has been largely based on imaging; however, recent studies have demonstrated the incongruities between preoperative MRI diagnosis and postoperative pathological findings highlighting the importance of brainstem biopsy for diagnostic accuracy. Stereotactic brainstem biopsy for pediatric brainstem tumors has been proven to be safe with a high diagnostic yield (96.1-97.4%) and relatively low morbidity and mortality. Successful pediatric brainstem tumor biopsy demands intricate knowledge of brainstem anatomy, cranial nerves and vasculature, and common pediatric brainstem tumors by the performing surgeon. Additionally, understanding of the surgical indications and techniques (e.g., frame-based versus frameless, robotic assistance, surgical approach, and targets selection) helps to ensure maximal safety and tissue yield. Pediatric brainstem biopsy permits histological conformation of brainstem lesions leading to accurate diagnosis and the potential for personalized treatment and future therapeutic research.

High-Grade Glioma of the Ventrolateral Medulla in an Adult: Case Presentation and Discussion of Surgical Considerations

Background. High-grade gliomas of the brainstem are rare in adults and are particularly rare in the anterolateral medulla. We describe an illustrative case and discuss the diagnostic and treatment issues associated with a tumor in this location, including differential diagnosis, anatomical considerations for options for surgical management, multimodality treatment, and prognosis. Case Description. A 69-year-old woman presented with a 3-week history of progressive right lower extremity weakness. She underwent an open biopsy via a far lateral approach with partial condylectomy, which revealed a glioblastoma. Concurrent temozolomide and radiation were completed; however, she elected to stop her chemotherapy after 5.5 weeks of treatment. She succumbed to her disease 11 months after diagnosis. Conclusions. Biopsy can be performed relatively safely to provide definitive diagnosis to guide treatment, but long-term prognosis is poor.

The efficacy of a biopsy of intrinsic brainstem lesions for decision making of the treatments

OBJECT

The diagnosis of diffuse intrinsic pontine gliomas (DIPGs) has been generally made mainly by magnetic resonance imaging (MRI) and clinical course. However, the accuracy of MRI-based diagnosis has not been fully confirmed yet. Our aim was to review efficacy of biopsy for decision making of the treatments.

METHODS

We retrospectively analyzed pediatric patients undergoing biopsy for intrinsic brainstem lesions which were considered atypical for DIPGs by MRI findings. The lesion was evaluated atypical when it extended beyond the pons or it had a well-margined localized enhancing portion.

RESULTS

Seven patients underwent biopsy. Preoperative MRI revealed a lesion extending beyond the pons in five patients and a focal enhancing lesion in four. Two patients had both of these. Open biopsy was performed via midline suboccipital approach in six patients and retrosigmoid approach in one. No intraoperative complications were observed. Histopathological examination revealed diffuse brainstem glioma in five patients, primitive neuroectodermal tumor (PNET) in one, and pilocytic astrocytoma in one. In the case with PNET, chemotherapy and radiotherapy were effective and the patient had been stable for 12 months without recurrence. The patient with pilocytic astrocytoma did not undergo radiotherapy and has been stable without regrowth of the tumor for 9 months.

CONCLUSIONS

Open biopsy of intrinsic brainstem lesions is considered to be safe and effective for selecting an appropriate course of therapy. Patients with intrinsic pontine lesions which extend beyond the pons or with localized enhancing portion seem to be benefited from the biopsy.

Current concepts in stereotactic radiosurgery - a neurosurgical and radiooncological point of view

Stereotactic radiosurgery is related to the history of "radiotherapy" and "stereotactic neurosurgery". The concepts for neurosurgeons and radiooncologists have been changed during the last decade and have also transformed neurosurgery. The gamma knife and the stereotactically modified linear accelerator (LINAC) are radiosurgical equipments to treat predetermined intracranial targets through the intact skull without damaging the surrounding normal brain tissue. These technical developments allow a more precise intracranial lesion control and offer even more conformal dose plans for irregularly shaped lesions. Histological determination by stereotactic biopsy remains the basis for any otherwise undefined intracranial lesion. As a minimal approach, it allows functional preservation, low risk and high sensitivity. Long-term results have been published for various indications. The impact of radiosurgery is presented for the management of gliomas, metastases, brain stem lesions, benign tumours and vascular malformations and selected functional disorders such as trigeminal neuralgia. In AVM's it can be performed as part of a multimodality strategy including resection or endovascular embolisation. Finally, the technological advances in radiation oncology as well as stereotactic neurosurgery have led to significant improvements in radiosurgical treatment opportunities. Novel indications are currently under investigation. The combination of both, the neurosurgical and the radiooncological expertise, will help to minimize the risk for the patient while achieving a greater treatment success.

Transcerebellar stereotactic biopsy for lesions of the brainstem and peduncles under local anesthesia

OBJECTIVE

For certain brainstem lesions, a diagnostic biopsy is required for treatment planning. We reviewed the indications, safety, and diagnostic effectiveness of a transcerebellar stereotactic biopsy using local anesthesia and sedation.

METHODS

We retrospectively reviewed hospital records for all adult patients with symptomatic lesions of the pons and/or cerebellar peduncle who underwent an awake transcerebellar stereotactic biopsy at our institution over a 7-year period. Our technique features several modifications from the standard method and was performed under local anesthesia with patients in the semi-sitting position.

RESULTS

Our rate of diagnostic success (92%) was comparable to those in other published reports. However, only 5 (42%) of 12 biopsy-derived diagnoses were consistent with those predicted from preoperative magnetic resonance imaging. There were no deaths, and the only neurological complication was a cranial nerve palsy. Diagnoses in the 13 cases included infiltrative glioma (), metastases (), lymphoma (), encephalitis (), and reactive astrogliosis ().

CONCLUSION

Tissue diagnosis of lesions in the brainstem and cerebellar peduncles continues to be a significant challenge, with the potential for major morbidity. With appropriate patient selection, however, awake transcerebellar biopsy is a safe and effective procedure that can change clinical management and provide important prognostic information.

Stereotactic biopsy of brain stem masses: decision analysis and literature review

BACKGROUND

Adult brain stem tumors are rare, and diverse pathology can be found in this location. Stereotactic biopsy of lesions in the brain stem has been performed since the 1960s with high diagnostic and low complication rates. Advances in imaging technology have raised questions regarding the utility of biopsy. We perform decision analysis to aid clinicians in their approach to management of adult brain stem lesions.

METHODS

A structured literature search revealed 20 publications with 457 patients who had undergone brain stem lesion biopsy. These publications were reviewed to determine diagnostic rates and the incidence of complications. Standard decision analytic techniques were applied to the case of a virtual adult patient with a lesion in the brain stem.

RESULTS

A 1-way sensitivity analysis revealed the likelihood that the preoperative diagnosis was correct and the rate at which incorrect treatment was based on faulty empirical diagnosis as the 2 factors with the greatest effects on patient outcome. The diagnostic rate and complication rate of biopsy, within the ranges reported in the literature, had lesser effects. A threshold analysis was constructed to compare outcomes from stereotactic biopsy vs empiric therapy for a brain stem lesion. The probability that the preoperative diagnosis is correct is plotted vs the probability that empirical treatment based on an incorrect diagnosis will have adverse effect.

CONCLUSIONS

Management of lesions in the adult brain stem requires careful consideration of multiple preoperative factors including clinical and radiographic diagnostic certainty, consequences of empiric therapy, and the surgeon's complication rate.

Validation of intraoperative diagnoses using smear preparations from stereotactic brain biopsies: intraoperative versus final diagnosis--influence of clinical factors

OBJECTIVE

Despite improvements in imaging techniques, histopathological diagnosis is still an important tool in neuro-oncology. At Freiburg University Hospital in Germany, approximately 450 patients per year undergo a serial stereotactic biopsy to obtain a diagnosis. We analyzed the accuracy of intraoperative diagnosis for rapid establishment of treatment options. Furthermore, we wanted to find out whether the location and histopathology of the tumors as well as the age and sex of the patients affected accuracy. Because of the large number of biopsies performed per year, parameters could also be evaluated for rare cerebral lesions.

METHODS

We retrospectively analyzed 5000 consecutive stereotactic brain biopsies from 4589 patients. The digital database comprises the intraoperative and final diagnoses, the location of the tumors, and the sex and age of the patients. Regression analysis was performed to identify parameters that had a significant impact on the results.

RESULTS

Intraoperative diagnosis was correct in 90.3% of biopsies. This included complete correlation in 81.3% of the biopsies and partial correlation in 9% of the biopsies. In 5.1% of the biopsies, no correlation between the intraoperative and final diagnosis was obtained. In 4.6% of the biopsies, no diagnosis could be made during or after surgery. A high correlation was found for World Health Organization Type II astrocytomas and, with regression analysis, for World Health Organization Type I astrocytomas, glioblastomas, and metastases.

CONCLUSION

Intraoperative diagnosis with stereotactic biopsy has high validity. Immediate treatment based on the intraoperative diagnosis can be justified (e.g., for metastases or glioblastomas). Stereotactic biopsy with an exact histopathological diagnosis is strongly recommended for planning adequate therapy for patients with unidentified brain lesions.

A contralateral, transfrontal, extraventricular approach to stereotactic brainstem biopsy procedures. Technical note

The authors report on the technique and results of stereotactic biopsy for intrinsic lateral pontine and medial cerebellar lesions via a contralateral, transfrontal, extraventricular approach. Multiplanar stereotactic magnetic resonance imaging was used to plan an intraparenchymal approach, thus limiting the number of crossed pial surfaces to one and eliminating the need to cross ependymal surfaces. After the administration of a local anesthetic agent with light intravenous sedation, six patients harboring intrinsic lateral pontine lesions underwent biopsies via this intraparenchymal approach with 100% diagnostic yield and no operative morbidity. In comparison to the ipsilateral transfrontal approach, the contralateral approach laterally expands the infratentorial area accessible during biopsy to include the lateral pons and middle cerebellar peduncle. The contralateral, transfrontal, extraventricular approach is a useful, straightforward and safe alternative to the suboccipital transcerebellar and ipsilateral, transfrontal, transtentorial routes for reaching lesions of the lateral pons and middle cerebellar peduncle.

Stereotactic biopsies of focal brainstem lesions

BACKGROUND

Stereotactic biopsies of the brainstem (SBB) are a selected group of stereotactic operations owing to the lower incidence of brainstem lesions requiring biopsy, the greater complexity, and the higher risks of these procedures. Usually, the lower the lesion in the brainstem, the greater the risks involved. The approach of the different target locations by distinct routes, transcerebral and transcerebellar, is still a matter of debate. Moreover, pure medullary lesions are seldom biopsied, whereas diffuse brainstem lesions, typical of children's brainstem gliomas and rather frequent in most published series, depend less and less on the histopathological confirmation for treatment. In this study, the authors present their own experience on SBB aiming to discuss mainly their indications, approach routes choice, and procedure techniques.

METHODS

The authors reviewed a series of 30 SBB (27 adults and 3 children) out of 450 stereotactic biopsies of the central nervous system performed for the last 10 years. All cases but one presented as focal brainstem masses, 19 mainly in the pons and 10 in the midbrain. Eleven lesions (10 in the midbrain and one midbrain-pontine) were approached by a transfrontal route. All the others were approached by a suboccipital transcerebellar route.

RESULTS

Twenty-six (87%) out of the 28 cases (93%) where a positive histopathological result was obtained had a specific diagnosis: 18 tumors (14 astrocytomas, 2 primary brain lymphomas, 1 oligodendroglioma, and 1 ganglioglioma), 2 toxoplasmosis, 2 sarcoidosis, 1 aspergillus abscess, 1 vasculitis, 1 acute inflammatory demyelinating disease, and 1 progressive multifocal leucoencephalopathy. Four nontumoral lesions arose in patients with AIDS. Morbidity was restricted to 2 cases consisting of transient cranial nerve deficits.

CONCLUSIONS

Stereotactic biopsies are specially useful for the diagnosis of focal brainstem lesions. Midbrain and midline lesions should be approached through the cerebrum, whereas most of the pontine lesions through the cerebellum. Overall, this procedure should be performed with "functional-like" precision and require some technical refinements to reach maximal accuracy with minimal morbidity.