What is the best course of action for a 60-year-old male with a newly detected brain lesion, seizure activity, and a history of unwitnessed fall, orbital floor fracture, and remote left frontal lobe infarct?

Stereotactic Brain Biopsy for Left Temporal Lesion with New-Onset Seizures

Proceed with the planned left temporal stereotactic biopsy as the appropriate next step to establish a definitive tissue diagnosis before initiating any definitive treatment. 1

Rationale for Stereotactic Biopsy

The primary goal is obtaining diagnostic tissue to guide all subsequent management decisions. 1 In this 60-year-old male with a newly detected left temporal lobe mass and new-onset seizures, the differential diagnosis remains broad and includes:

• Primary brain tumors (low-grade glioma, high-grade glioma/glioblastoma, oligodendroglioma) 1
• Metastatic disease (given smoking history, though no known primary cancer) 1
• Non-neoplastic lesions (inflammatory, infectious, vascular) 1, 2

Stereotactic biopsy is indicated when a tissue diagnosis is needed to direct treatment, particularly for deep or eloquent cortex lesions where resection carries higher risk. 1 The left temporal location near the amygdala makes this an appropriate candidate for stereotactic approach rather than open resection initially. 3

Seizure Management During Perioperative Period

Initiate antiepileptic therapy immediately given the documented seizure with EEG-confirmed focal temporal sharps. 4, 5 This patient has already experienced at least one witnessed generalized tonic-clonic seizure with possible cardiac arrest requiring CPR, plus episodes of expressive aphasia suggesting ongoing seizure activity. 4

Start levetiracetam (Keppra) 500-1000 mg twice daily, which can be safely continued through the biopsy procedure. 6 Levetiracetam is preferred in this setting because:

• Effective for partial-onset seizures with 26.8-44.6% reduction in seizure frequency 6
• Minimal drug interactions 6
• Does not require dose adjustment for surgery 6
• Can be initiated without titration in urgent situations 6

Monitor for behavioral/psychiatric adverse effects including irritability, depression, and psychotic symptoms, which occur in 5-13% of patients. 6 These typically emerge within the first 4 weeks of treatment. 6

Imaging Considerations

The MRI findings of asymmetric prominence of the left inferior temporal lobe/amygdala region favoring a mass lesion require tissue diagnosis. 1 While MRI is superior to CT for detecting epileptogenic lesions (70-80% sensitivity vs 30% for CT), imaging alone cannot reliably distinguish between tumor types or exclude non-neoplastic etiologies. 1, 7

Obtain a postoperative MRI with and without contrast 24-72 hours after biopsy to document extent of sampling and any complications. 1

Biopsy Technique and Safety

For this left temporal lesion, a supratentorial transfrontal stereotactic approach is appropriate with expected diagnostic yield >90%. 3, 2 The safety profile for stereotactic brain biopsy shows:

• Mortality: 3% 2
• Permanent morbidity: 3% 3, 2
• Transient neurological deficits: 13-18% (typically resolve spontaneously) 3, 2

Ensure adequate tissue is obtained for both histopathology and molecular testing (IDH1/IDH2, 1p/19q deletion status) as required by 2016 WHO classification for integrated diagnosis. 1 Never freeze all tissue received—preserve sufficient unfrozen tissue for ancillary molecular studies. 1

Post-Biopsy Management Algorithm

Management depends entirely on the pathology results: 1

If High-Grade Glioma (Grade III-IV):

• Maximal safe resection if feasible, followed by concurrent chemoradiation with temozolomide 1
• If only biopsy obtained, proceed directly to fractionated external beam radiation therapy (EBRT) with concurrent and adjuvant temozolomide 1

If Low-Grade Glioma (Grade II):

• Consider observation if gross total resection achieved and patient is low-risk (age <40, KPS ≥70, tumor <6 cm, no midline crossing) 1
• High-risk patients (age ≥40, subtotal resection, tumor >6 cm) should receive adjuvant radiation or chemotherapy 1

If Metastatic Disease:

• Identify primary source with systemic staging 1
• Treatment options include surgical resection, stereotactic radiosurgery, or whole-brain radiation depending on number and location of lesions 1

If Non-Neoplastic (Inflammatory/Infectious):

• Direct treatment toward specific etiology identified 1, 2

Critical Pitfalls to Avoid

Do not delay biopsy based on imaging characteristics alone—17% of presumed brain stem tumors in adults prove to be non-neoplastic on biopsy. 2 The variety of pathologies that can present as temporal lobe masses with seizures mandates tissue diagnosis. 1, 2

Do not start radiation or chemotherapy without tissue confirmation. 1 Treatment paradigms differ dramatically based on histology and molecular markers (e.g., oligodendrogliomas with 1p/19q deletion have markedly better prognosis and chemosensitivity than astrocytomas). 1

Ensure the neurosurgeon obtains "lesional tissue" during biopsy—if initial frozen section shows only necrosis or normal brain, additional sampling from a different trajectory may be needed. 1 Real-time intraoperative feedback between pathologist and surgeon is essential. 1

Continue antiepileptic medication throughout the perioperative period and do not withdraw abruptly, as this increases seizure risk. 6 Antiepileptic drugs should be withdrawn gradually if discontinuation is planned. 6