title: Microrecording and image-guided stereotactic biopsy of deep-seated brain tumors.
abstract: OBJECTIVE
  Image-guided stereotactic brain tumor biopsy cannot easily obtain samples of small deep-seated tumor or selectively sample the most viable region of malignant tumor. Image-guided stereotactic biopsy in combination with depth microrecording was evaluated to solve such problems.
  
  
  METHODS
  Operative records, MRI findings, and pathological specimens were evaluated in 12 patients with small deep-seated brain tumor, in which image-guided stereotactic biopsy was performed with the aid of depth microrecording. The tumors were located in the caudate nucleus (1 patient), thalamus (7 patients), midbrain (2 patients), and cortex (2 patients). Surgery was performed with a frameless stereotactic system in 3 patients and with a frame-based stereotactic system in 9 patients. Microrecording was performed to study the electrical activities along the trajectory in the deep brain structures and the tumor. The correlations were studied between the electrophysiological, MRI, and pathological findings. Thirty-two patients with surface or large brain tumor were also studied, in whom image-guided stereotactic biopsy without microrecording was performed.
  
  
  RESULTS
  The diagnostic yield in the group with microrecording was 100% (low-grade glioma 4, high-grade glioma 4, diffuse large B-cell lymphoma 3, and germinoma 1), which was comparable to 93.8% in the group without microrecording. The postoperative complication rate was as low as that of the conventional image-guided method without using microelectrode recording, and the mortality rate was 0%, although the target lesions were small and deep-seated in all cases. Depth microrecording revealed disappearance of neural activity in the tumor regardless of the tumor type. Neural activity began to decrease from 6.3 ± 4.5 mm (mean ± SD) above the point of complete disappearance along the trajectory. Burst discharges were observed in 6 of the 12 cases, from 3 ± 1.4 mm above the point of decrease of neural activity. Injury discharges were often found at 0.5-1 mm along the trajectory between the area of decreased and disappeared neural activity. Close correlations between electrophysiological, MRI, and histological findings could be found in some cases.
  
  
  CONCLUSIONS
  Image-guided stereotactic biopsy performed using depth microrecording was safe, it provided accurate positional information in real time, and it could distinguish the tumor from brain structures during surgery. Moreover, this technique has potential for studying the epileptogenicity of the brain tumor.
authors: Departments of 1 Neurosurgery and.
authors: Keiya
authors: K
authors: Iijima
authors: Departments of 1 Neurosurgery and.
authors: Masafumi
authors: M
authors: Hirato
authors: Departments of 1 Neurosurgery and.
authors: Takaaki
authors: T
authors: Miyagishima
authors: Departments of 1 Neurosurgery and.
authors: Keishi
authors: K
authors: Horiguchi
authors: Departments of 1 Neurosurgery and.
authors: Kenichi
authors: K
authors: Sugawara
authors: Clinical Department of Pathology, Gunma University Hospital, Maebashi, Gunma, Japan.
authors: Junko
authors: J
authors: Hirato
authors: Human Pathology, Gunma University Graduate School of Medicine; and.
authors: Hideaki
authors: H
authors: Yokoo
authors: Departments of 1 Neurosurgery and.
authors: Yuhei
authors: Y
authors: Yoshimoto
mesh_terms: D000293:Adolescent; D000368:Aged; D001932:Brain Neoplasms / Q000473:pathology* / Q000503:physiopathology; D002648:Child; D003943:Diagnostic Techniques, Neurological; D055724:Electrophysiological Phenomena; D005260:Female; D006801:Humans; D061705:Image-Guided Biopsy; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D013238:Stereotaxic Techniques; D055815:Young Adult
keywords: DLBCL = diffuse large B-cell lymphoma; HGG = high-grade glioma; LGG = low-grade glioma; burst; depth microrecording; epileptogenicity; image guided; stereotactic biopsy; stereotactic radiosurgery; tumor-brain interface