Non-diagnostic stereotactic intracranial biopsies: a 15-year institutional experience

Stereotactic brain biopsies are not without risk, and non-diagnostic biopsies can delay the instigation of appropriate treatment. Institutions rarely report their negative (non-diagnostic) results; this reporting is essential for quality and improvement in neurosurgical departments. We report a retrospective single-center decade-long cohort of non-diagnostic stereotactic biopsies. We report the indications for biopsy, histopathological findings, rates of re-biopsy, lesion characteristics and biopsy success metrics such as depth-do-diameter, biopsy accessibility metrics and true (TN) and false (FN) negative rates. Of 387 biopsies, 23 were non-diagnostic (5.94%). Among 196 robot-assisted procedures, the non-diagnostic rate was 5.05%, compared to 6.88% across 189 non-robot-assisted biopsies (p = 0.52). The anticipated diagnosis was tumor/metastasis in 65% of cases. 26% of patients were asymptomatic prior to biopsy. The target was subcortical in 61% of cases, with median volume 8.36cm3 and lesion depth 65.05 mm. Deeper lesions were larger (r = 0.47, 95%CI:0.02–0.76, p = 0.036). Biopsy showed indeterminate mild gliosis in 60.9%, normal parenchyma in 34.8% and hemorrhage in one case. Two patients underwent re-biopsy. Post-biopsy, 52% were treated medically, 26% remained under observation, the remainder were palliated or underwent surgery. On review of prior and future clinical/radiological/histopathological data, 7 (30.4%) were TN, 14 (60.8%) were FN. No TN biopsies occurred at a lesion depth of less than 50 mm. The optimal method and equipment for stereotactic biopsies remains an area of personal and institutional preference. Internal review of these metrics can identify areas for improvement of service delivery in a procedure that is central to the diagnosis and treatment of patients with brain lesions.