CPT® Code 61105

A twist drill hole is a surgical procedure performed to access the subdural space or the ventricles of the brain. This procedure involves the use of a hand twist drill, which is specifically designed to create a small opening in the skull. The drill is equipped with a safety stop that is adjusted to the anticipated thickness of the skull at the site where the hole will be made. As the drill penetrates the outer and inner tables of the skull, the surgeon monitors for a change in resistance, which indicates that the inner table has been breached and the dura mater, the protective membrane surrounding the brain, has been punctured. Following this, a needle is inserted through the newly created drill hole to access the subdural space or one of the brain's ventricles, allowing for the aspiration of cerebrospinal fluid (CSF). This procedure is critical for diagnostic purposes, such as analyzing CSF for infections or other neurological conditions. It is important to note that if the procedure involves the implantation of an intraventricular catheter or other monitoring devices, a different CPT® code, specifically 61107, should be utilized. This highlights the distinction between a simple puncture and more complex interventions that require additional equipment for monitoring intracerebral parameters.