Learning Curve in Progression from Microscopic to Endoscopic Technique in Transsphenoidal Surgery for Pituitary Adenomas – A Surgical Audit

Objective : To study the improvement in intraoperative and postoperative parameters for 3 experienced neurosurgeons as they shift from microscopic to endoscopic approach for pituitary adenoma patients. Method : A retrospective analysis of 110 consecutive patients who underwent endoscopic endonasal binostril transsphenoidal surgery for pituitary adenomas was done. Patients were evaluated for preoperative symptoms, tumor size (on MRI), hormonal deficits and visual status. Intraoperative CSF leak, blood loss, operative time, sinus/ICA injury and conversion to microscopic technique were evaluated. Postoperative visual status, hormonal imbalance, electrolyte imbalance, meningitis were evaluated alongwith percentage of tumor excision. All the cases were divided into two halves and each surgeon's early results were compared with later results to look for a learning curve. Results : A total of 110 cases were operated upon by 3 different surgeons. Each surgeon had an experience of at least 7 years as faculty and had operated >100 pituitary cases microscopically. Comparing the first 55 cases with the second 55, the mean postoperative stay decreased from 9.9 to 6.6 days. The proportion of giant adenomas increased from 7.3% to 20%. The mean size of tumor operated upon increased from 12.2 ml to 16.3 ml. Patients requiring conversion to microscopic decreased from 12.7% to 5.5%. There were fewer incidences of sinus bleed (3.6% to 1.8%) and ICA injury (1.8% to 0%). Improvement in vision showed increase from 12.7% to 21.8%. Postoperative meningitis decreased from 9.1% to 1.8%. Surgeon 1 performed 34 cases. Mean postoperative stay decreased from 13.5 to 8.7 days. Mean blood loss improved from 641 ml to 561 ml. Postoperative improvement in visual status increased from 5.9% to 29.4%. The mean size of tumor operated upon also increased in the second half from 11.2 ml to 17ml. Minimum percentage excision achieved improved from 24% to 36%. Surgeon 2 performed 53 cases. Mean postoperative stay decreased from 6.15 to 5 days. The proportion of giant adenomas operated increased from 7.7% to 22.2%. The mean size of tumor operated upon increased from 10.8 ml to 13.1 ml. Compared with 4 cases (15.4%) which were converted to microscopic in the first half, none were converted in the second half. Mean operative time improved from 133 to 117 minutes. Compared with 2 cases of sinus bleed (7.7%) in the first half, there were none in the second half. Surgeon 3 performed 23 cases. Mean postope