OBJECTIVE: To investigate the value and safety of stereotactic biopsy of brainstem lesions.
METHODS: To retrospectively summarize the positive diagnostic rate and complications of stereotactic biopsy surgery for brainstem lesions in 68 cases.
RESULTS: Among them, 64 cases were diagnosed clearly by stereotactic biopsy surgery, and the diagnostic positivity rate was 94.12%. There were no fatal cases, and the complication rate was 2.94%.
CONCLUSION: Stereotactic biopsy of brainstem lesions can help to confirm the diagnosis of lesions and thus select individualized treatment plans and improve the prognosis. Wang Hongwei, Department of Neurosurgery, Naval General Hospital
Accurate diagnosis of lesions in the brainstem is the basis for effective treatment and prognosis [3], [4]. Advances in imaging technology, especially magnetic resonance, have enabled the localization and diagnosis of brainstem diseases; however, establishing an accurate diagnosis requires a histological basis in most cases. The deep location of the brainstem and its neurological importance make it difficult to perform open surgical biopsies in most cases. The precise positioning of stereotactic minimally invasive techniques has made biopsy of brainstem lesions a common tool. The positive diagnostic rate and safety of stereotactic brainstem lesion biopsy have been improving in the past decade at our hospital, and are summarized below for the reference of our colleagues.
Data and methods
1. General data: From November 1995 to February 2011, 68 cases of stereotactic biopsy of brainstem lesions were performed, 35 males and 33 females, aged 1~71 years, with an average age of 32.1 years. 58 cases of glioma, 5 cases of lymphoma, 2 cases of inflammation, and 3 cases of demyelinating lesions were diagnosed in preoperative imaging. 25 cases of lesion subjects were located in the midbrain, 27 cases in the pontine brain, and 16 cases in the upper medulla oblongata.
2. Surgical methods: 42 cases underwent framed stereotactic biopsy, 26 cases underwent frameless stereotactic biopsy, 15 cases were localized by CT guidance, 53 cases were localized by MRI scan guidance. 39 patients took the ipsilateral transfrontal puncture route, and 29 patients took the transoccipital inferior cerebellar hemisphere puncture route. Framed stereotactic biopsy: The Leksell framed stereotactic system was used to design the target and puncture trajectory in the planning system, and the principles were: the puncture trajectory avoided passing through important functional areas, important intracranial vessels, and the ventricular system. A transfrontal puncture path was chosen for midbrain and upper pontine lesions, and a transcerebellar hemispheric path was taken for lesions from the lower pontine to medulla oblongata. The biopsy was performed under local anesthesia according to the surgical plan, and the biopsy tissue was sent for frozen pathology and paraffin pathology within a certain range from above to below the target point using negative pressure lateral excision biopsy needle. Frameless stereotactic biopsy: The CAS-R-2 frameless stereotactic instrument was used to design the target point and puncture trajectory in the frameless stereotactic planning system, and the design principles were the same as those of the framed system. The robot arm joints were adjusted according to the computer parameters, and the scalp entry point was determined according to the direction indicated by the robot arm.
Results
In 64 cases, a clear pathological diagnosis was obtained after surgery (see Table 1), and the positive biopsy rate was 94.12%, including 95.2% for framed stereotactic biopsy and 92.3% for frameless stereotactic biopsy. 39 patients had the same preoperative clinical diagnosis, 4 patients had no clear pathological diagnosis, and the preoperative diagnosis was glioma, among which 1 patient terminated the surgery due to severe intraoperative reaction, 2 patients had glial cell hyperplasia, and 1 patient had necrotic tissue without tumor cells. In one case, the operation was terminated due to severe intraoperative reaction, in two cases glial cell hyperplasia and in one case necrotic tissue without tumor cells. After surgery, two patients showed symptoms of neurological damage: one patient had ipsilateral oculomotor nerve palsy and one had mild paralysis of the contralateral limb, and there was no bleeding or death.
Pathological diagnosis of 68 brainstem lesion biopsies
Pathology type Number of cases
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Glioma of all grades 45
Lymphoma 3
Neurodegenerative disease 2
Multiple sclerosis and verrucous demyelinating disease 5
Non-specific inflammatory diseases 2
Brainstem infarction 2
Brainstem tuberculosis 1
Brainstem abscess 1
Metastatic tumor 2
Radiation necrosis 1
Negative results 4
DISCUSSION
The necessity and indications of brainstem biopsy: the brainstem is small and has a variety of lesions, including tumors, inflammation, vascular malformations, hemorrhage and infarction, demyelinating lesions, and nonspecific glial cell proliferation [7], and most brainstem lesions are inaccurately diagnosed by imaging techniques alone [3] [4], [5], [11] and require pathological diagnosis by biopsy of the lesion tissue. In 2008, Sanai reported 13 cases of brainstem biopsy with a 42% agreement between imaging and postoperative pathological diagnosis [4], and in this paper, the pathological diagnosis was consistent with the preoperative imaging diagnosis in 39 cases, accounting for 60.9%. The indications for stereotactic biopsy of brainstem lesions are as follows: 1) brainstem lesions that cannot be clearly diagnosed by imaging; 2) when the clinical diagnosis of brainstem tumors cannot be surgically resected, tissue biopsy can be performed to clarify the pathological diagnosis and guide interstitial radiotherapy and chemotherapy at the same time as biopsy; 3) cystic tumor lesions can be biopsied and cystic fluid extraction and intracapsular injection can be performed at the same time. 5.Benign brainstem lesions can be differentiated from tumors by stereotactic biopsy, and internal radiotherapy can be guided at the same time.
The technical points of stereotactic biopsy of brainstem lesions: 1, the selection of puncture target: the correct selection of puncture target is the key to ensure the success of biopsy sampling, usually guided by MRI scan as the image, preoperative consideration of tumor diseases generally to the lesion enhancement obvious parts as the target, cystic tumors can be enhanced obvious cyst wall as the target, abscess lesions to the center of the cystic cavity as the target. PET can distinguish the activity of tumor tissue by tissue metabolism and the degree of nuclein agglutination, and preoperative PET examination can guide the selection of target sites intraoperatively and improve the positive rate of biopsy diagnosis [5], [12]. For diffuse lesions, such as diffuse gliomas or demyelinating lesions, target sites can be identified with the help of nuclear magnetic bop analysis. In order to ensure accurate sampling, the selection of the target site should also take into account the safety of the procedure.2. Design of the puncture path: the ipsilateral transfrontal path is mostly adopted for midbrain lesions above the level of the cerebellar curtain notch [1], [2], with the entry point located in front of the precentral gyrus and behind the coronal suture, and the puncture direction is as parallel as possible to the direction of nerve fiber travel between the cortex and the midbrain, avoiding the lateral fissure pool, the cricoid pool, and the thalamus, while The brain tissue is displaced by a large loss of cerebrospinal fluid during retrieval, resulting in errors (see Figure 1) [10]; pontocerebellar and superior medullary lesions below the cerebellar curtain are mostly biopsied via the cerebellar hemisphere to the pontine arm pathway, avoiding the base of the four ventricles (see Figure 2) [4], [6], [7], [13].Dellaretti M recently reported 142 cases of stereotactic brainstem Amundson EW 2005 reported 6 cases of submural pontine lesions biopsied through the contralateral parenchymal pathway, reporting a 100% positive diagnostic rate, and the authors noted that this pathway was more direct and 3. choice of anesthesia: framed biopsies are mostly performed under local anesthesia, which helps to observe the changes in patient’s consciousness and neurological function, adjust the biopsy needle depth in time or end the process in time [9], and shorten the recovery time of the procedure. The puncture device is firmly integrated with the patient’s head through the frame, so that intraoperative changes in the patient’s head position do not affect the puncture accuracy. In children and patients with mental abnormalities, puncture is performed under general anesthesia. The frameless orientation approach has a direct impact on the accuracy of the procedure due to intraoperative head position changes, and puncture is usually performed under general anesthesia.
The accuracy and safety of brainstem biopsy: Sanai N 2008 reported 13 brainstem biopsies with a positive diagnostic rate of 92% and one patient with postoperative development of neurological palsy, accounting for 8% of cases and no deaths [4]. Shad A 2005 reported 13 brainstem biopsies, 7 in the midbrain, 1 in the pontine brain and 2 in the medulla oblongata, 12 patients were diagnosed postoperatively with a definite pathology and no deaths, 3 cases were left with transient cranial nerve palsy and minimal complications [9].Samadani U 2003 reported a positive diagnostic rate of 96% for brainstem biopsies, a mortality rate of 3% and a complication rate of 4%. In this paper, the positive biopsy diagnosis rate was 94.12% and the incidence of complications was 2.94%, with no fatalities. The above reported data show that brainstem stereotactic biopsy has reliable accuracy and safety.
Comparison of the two methods of directional biopsy: with frame stereotactic fixation of the head frame to the patient’s skull with four screws, intraoperative movement of the patient’s head does not affect the surgical operation, at the same time, the frame can be combined with the gamma knife, for biopsy clear tumor nature of the lesion can be directly treated with the gamma knife. Disadvantages: the installation of the head frame increases the patient’s psychological burden and physical pain; the thermal effect of the magnetic field during MRI positioning scan burns the patient’s scalp through the head frame; the need for adapter docking between the frame and the MRI makes it impossible for people with special body types to perform positioning scans; the obstruction of the frame makes it difficult to perform certain puncture trajectories; the low cranial strength of children and the osteoporosis of the elderly make screw fixation of the frame lead to epidural hematoma. -R-2 frameless stereotactic instrument is guided for stereotactic biopsy surgery by the support of a mechanical arm connected by five precision joints; the mechanical arm is a rigid structure with high stability and clinically proven high positioning accuracy [15]. Frameless stereotactic avoids the pain caused by the fixed head frame to the patient and the limitation of the head frame to the surgical operation space, eliminates the tedious steps of disassembling and assembling the head frame, and shortens the operation time; the mechanical arm is connected to the computer workstation, and the parameter adjustment part of the mechanical arm is intelligent and easier to operate [2], [15]. The frameless stereotactic biopsy technique has its own limitations: the virtual space of the human brain is fused with the actual space through scalp markers, and the accuracy of localization is affected when the markers are displaced by scalp traction and head position changes; it cannot be directly combined with gamma knife localization. The two brainstem biopsy methods have proven to be close in terms of safety and accuracy, while having their own advantages, and can be used selectively according to the patient’s own situation.
Conclusion: The stereotactic brainstem biopsy technique is safe, reliable, and has a high positive diagnostic rate. When a lesion in the brainstem cannot be accurately diagnosed based on imaging data and clinical symptoms, stereotactic biopsy procedures can be used to obtain an accurate pathological diagnosis, which is important for the correct treatment and prognostic assessment of the disease [3], [4].