The presence of a potential learning curve is a key reason to apply CUSUM analysis in neurosurgical procedures like intracranial pressure (ICP) monitor placement.

A learning curve represents the process by which a surgeon improves performance over time through repetition, feedback, and experience. CUSUM offers a sensitive method for detecting this progression.

A typical learning curve in a CUSUM chart has three phases:

• Phase 1 – Initial Learning
  1. Upward trend due to higher complication rates
  2. Reflects technical challenges and lack of familiarity

• Phase 2 – Transition
  1. The slope begins to flatten as performance stabilizes
  2. Indicates that the operator is gaining competence

• Phase 3 – Mastery
  1. Plateau or downward trend
  2. Suggests consistent success and minimal complications

By plotting each case sequentially and comparing against a target complication rate, CUSUM can:

• Determine the number of cases required to reach proficiency
• Detect outliers or regression in performance
• Justify decisions regarding independent practice or supervision

CUSUM-based learning curve analysis supports:

• Objective evaluation of trainees
• Optimization of case assignment in training programs
• Personalized feedback that improves learning efficiency

Recognizing and documenting potential learning curves helps ensure that training remains safe, data-driven, and responsive to individual progress.