CPT® Code 61539

Craniotomy with elevation of bone flap; for lobectomy, other than temporal lobe, partial or total, with electrocorticography during surgery

The CPT® Code 61539 refers to a surgical procedure known as craniotomy with elevation of the bone flap, specifically for lobectomy of a lobe other than the temporal lobe. This procedure is performed either partially or totally and incorporates the use of electrocorticography during the surgery. Electrocorticography, often referred to as brain mapping, is a technique that involves the direct recording of electrical potentials from the cerebral cortex and surrounding structures. This method is crucial for identifying the boundaries of the epileptogenic zone, which is the area of the brain responsible for generating epileptic seizures, and for determining the extent of the necessary resection of the affected lobe. The procedure begins with an incision in the skin and the creation of scalp flaps, followed by the drilling of burr holes in the skull. The bone between these burr holes is then cut using a specialized saw or craniotome, allowing the surgeon to elevate the bone flap. Once the dura mater, the protective covering of the brain, is opened and retracted, the surgeon measures the anterior aspect of the lobe to be excised and determines the locations for cortical incisions. If electrocorticography is utilized, electrodes are placed on the surface of the cerebral cortex, and additional electrodes may be inserted into deeper brain regions to record brain activity, both with and without stimuli. The surgical team carefully identifies the epileptogenic zone, incises the cortex, and performs dissection deep to the cortex using an ultrasonic aspirator. The dissection continues along the coronal plane towards the temporal horn of the lateral ventricle and the hippocampus. Special attention is given to the pia mater of the medial cortex, where a subpial dissection is performed, and the pia is opened. The anterior and lateral portions of the lobe are excised, followed by careful dissection of the hippocampus, amygdala, and uncus, ensuring that perforating arteries from the posterior cerebral artery are preserved. Throughout the procedure, the surgeon takes care to protect critical structures, including the anterior choroidal artery and the pia arachnoid over the ambient cistern, which contains vital neurovascular elements. The procedure concludes with the repair of the dura, replacement and securing of the bone flap, and closure of the temporalis muscle, galea, and skin in layers. This comprehensive approach ensures that the lobectomy is performed safely and effectively, with the goal of alleviating the patient's symptoms.