Brain Biopsy of a Suspected Cerebellar Lymphoma

1. Introduction

2. Patient Preparation

1. • General anesthesia is administered to the patient. In intradural lesions we use total intravenous anesthesia, usually consisting of remifentanil and propofol. Single-shot antibiotic (cefazolin) is administered 30 minutes before skin incision. Presurgical interdisciplinary team time-out is performed before washing and draping the patient, allowing for optimal communication between anesthesiologist, surgeon, and scrub nurse. A fluorescing substance capable of passing the blood-brain-barrier (sodium fluorescein) is intravenously injected before skin incision to prepare the tissue for biopsy.
   • Patient is put in supine position for ideal referencing of the navigation system. This is preferred over the prone position, where the patient is facing the floor and anatomical structures are less easily visible by the navigation system camera.
   • The skin incision is marked with a pen.

1.  Sterilization
   • The skin is sterilized with an iodine solution for 10 minutes.
2. Patient Draping
3. Preparation and Setup of Navigated Biopsy Guidance System

3. Skull Aperture

1. Incision Through Skin and Subcutaneous Adipose and Muscle Tissue
   • Homeostasis is obtained through bipolar cautery.
2. Aperture Drill Through the Skull
   • The bone is opened over the cerebellar using a bone drill—underneath the transverse sinus and above the atlanto-occipital membrane.
   • Incision of the dura is carried out in a “cross-shaped“ fashion.
   • It is important to note that this is a standard step in the procedure even though in this case it was perforated by the drill.
3. Exposure of Cerebellar Surface
   • Arachnoid and superficial cerebellar tissue at entry point are coagulated using bipolar coagulation to prevent bleeding and distortion of the biopsy needle.
4. Approach to Biopsy with Needle in Trajectory
   • Needle should not touch bone, dura, or arachnoid.

4. Biopsies

1. First Biopsy
   • Needle is inserted to approach contrast-enhancing tissue, but sample is taken from the border zone adjacent to the lesion (in the transition zone) from normal to pathologic tissue.
2. Second Biopsy (Needle Deeper into the Brain Tissue to Reach Center of Lesion)
   • These samples should be in the core of the lesion for diagnosing central necrosis. Evaluate to determine if these samples will provide a reliable diagnosis.
3. Biopsies 3–7, Deepest in the Tissue
   • Biopsies are taken from all areas of the lesion.
4. Irrigation of the Area and Patient Close-Up
   • Irrigate to allow bone dust and detritus from augmenting infection.
   • Place Gelfoam in the near-cortical tissue for hemostasis and prevention of CSF leakage.
   • Suture muscle, subcutaneous tissue, and skin.
   • Apply iodine and suture skin using 3-0 non-resorbable thread.

5. Sample Evaluation with Fluorescent Light

• • Biopsy specimens examined under a fluorescence light microscope to determine if the samples are from the pathologic tissue. Fluorescing samples resemble regions of disrupted blood-brain-barrier and prove that the lesion was targeted during biopsy.

6. Postoperative Care

• • Patient is taken to the PACU for 2–4 hours.
  • Dexamethasone is administered for 3 days (8 mg thrice daily).
  • Post-op CT scan is done after 16–24 hours to detect hemorrhage.
  • Low dose heparin (thrombosis prophylaxis) is allowed after control scan has ruled out hemorrhage.
  • Wound dressings are changed on post-op day 3, showering is allowed after post-op day 3. Full mobilization is allowed directly after surgery.
  • Tumor is treated according to histological diagnosis.