Frameless Robot-Assisted Stereotactic Biopsies for Lesions of the Brainstem – A Series of 103 Consecutive Biopsies

PurposeTargeted treatment for brainstem lesions requires above all a precise histopathological and molecular diagnosis. In the current technological era, robot-assisted stereotactic biopsies represent an accurate and safe procedure for tissue diagnosis. We present our center’s experience in frameless robot-assisted biopsies for brainstem lesions. MethodsWe performed a retrospective analysis of all patients benefitting from a frameless robot-guided stereotactic biopsy at our University Hospital, from 2001 to 2017. Patients consented to the use of data and/or images. The NeuroMate® robot (Renishaw™, UK) was used. We report on lesion location, trajectory strategy, histopathological diagnosis and procedure safety. ResultsOur series encompasses 96 patients (103 biopsies) treated during a 17 years period. Mean age at biopsy: 34.0 years (range 1-78). Most common location: pons (62.1%). Transcerebellar approach: 61 procedures (59.2%). Most common diagnoses: diffuse glioma (67.0%), metastases (7.8%) and lymphoma (6.8%). Non conclusive diagnosis: 10 cases (9.7%). After second biopsy this decreased to 4 cases (4.1%). Overall biopsy diagnostic yield: 95.8%. Permanent disability was recorded in 3 patients (2.9%, all adults), while transient complications in 17 patients (17.7%). Four cases of intra-tumoral hematoma were recorded (one case with rapid decline and fatal issue). Adjuvant targeted treatment was performed in 72.9% of patients. Mean follow-up (in the Neurosurgery Department): 2.2 years. ConclusionFrameless robot-assisted stereotactic biopsies can provide the initial platform towards a safe and accurate management for brainstem lesions, offering a high diagnostic yield with low permanent morbidity.

Case Report: Prominent Brainstem Involvement in Two Patients With Anti-CASPR2 Antibody-Associated Autoimmune Encephalitis

Anti-contactin-associated protein-like 2 (CASPR2) antibody-associated autoimmune encephalitis is commonly characterized by limbic encephalitis with clinical symptoms of mental and behavior disorders, cognitive impairment, deterioration of memory, and epilepsy. The classical lesions reported are located at the medial temporal lobe or hippocampus, whereas prominent brainstem lesions have not been addressed to date. Herein, we reported two patients mimicking progressive brainstem infarction with severe neurological manifestations. On brain magnetic resonance imaging (MRI), prominent brainstem lesions were noted, although multifocal lesions were also shown in the juxtacortical and subcortical white matters, basal ganglia, hippocampus, and cerebellar hemisphere. Unexpectedly and interestingly, both cases had detectable CASPR2 antibodies in sera, and an exclusive IgG1 subclass was documented in the further analysis. They were treated effectively with aggressive immunosuppressive therapies including corticosteroids, intravenous immunoglobulin G, and rituximab, with the first case achieving a rapid remission and the other undergoing a slow but gradual improvement. To the best of our knowledge, this is the first report on prominent brainstem involvement with definite MRI lesions in anti-CASPR2 antibody-associated autoimmune encephalitis, which helps to expand the clinical spectrum of this rare autoimmune disease and update the lesion patterns in the CNS.

Endodermal cyst: rare intraaxial brainstem location. Illustrative cases

BACKGROUND This report detailed an extremely rare location of an endodermal cyst. Such location of the tumor can pose radiological confusion and a therapeutic dilemma. However, when identified, it can be a pleasant surprise for the surgeon and provide the possibility of a symptom-free long life for the patient. OBSERVATIONS This report discussed two young patients who presented with relatively short-duration reports of ataxia and diplopia. Investigations revealed intraaxial brainstem lesion. During surgery, thick, pus-like fluid was evacuated and part of a wall was resected. Histology revealed that the lesion was an endodermal cyst. Both patients are well and are lesion- and symptom-free for 24 and 72 months. LESSONS Endodermal cysts are some of the few long-standing and benign intraaxial brainstem lesions.

Continuous Dynamic Mapping of Cranial Nerve Pathways and Long Tracts Inside the Brainstem: Useful Technique of Intraoperative Neurophysiological Monitoring

Surgery of intrinsic brainstem lesions is extremely dangerous, consequently the knowledge of anatomy and safe entry zones is extremely important. The technological progress was achieved with the widespread clinical use of intraoperative neurophysiological monitoring (IONM) which has proven to further improve the safety of operating on intrinsic brainstem lesions. The relevance of the study is conditioned by the fact that the tumor alters the normal anatomy and distorts the location of well-known landmarks and structures. In this regard, this paper is directed at identification of the placement of conductive pathways in the thickness of the brain stem and directly in the depth of the lesion (in the tumor or cavern), respectively to the surgical manipulations aimed at injury prevention. The results were achieved by a retrospective review of medical reports. The paper represents the results of surgical treatment of 42 patients with brainstem lesions, reviews the localization of the lesion and neurological status of patients, describes available methods of intraoperative monitoring (IOM) and on-line techniques for the brainstem surgery. The materials of the paper are of practical significance for the development of brainstem surgery with IONM modifications for wider and more comfortable use by neurosurgeons.