gms | German Medical Science

Objective: Microelectrode recording (MER) of single neuron activity is a common and useful technique in functional stereotactic neurosurgery. Since many years, however, controversial debates are ongoing regarding the necessity of MER and a potentially increased risk of intracranial haemorrhage. Here we aimed to investigate whether there is an increased risk of haemorrhage in a large series of patients operated over two decades.

Methods: This is a retrospective study on 585 patients who underwent functional stereotactic neurosurgery (DBS electrode implantation or radiofrequency lesioning) over a period of 20 years. Procedures were performed or supervised by the senior neurosurgeon in three different centers using the same technique. The target was determined with CT-stereotactic surgery and approached via a guiding cannula. MER was performed via a single channel technique, supplemented by MR imaging with additional trajectories if decided necessary. Single unit recording was mainly used for targeting the subthalamic nucleus (STN) and the internal globus pallidus (GPi), while thalamic targets like the nucleus ventralis intermedius (VIM) were mainly approached without MER. Postoperative CT scans obtained within 24 hours after surgery were searched for haemorrhage of any size at any site.

Results: A total of 244 women and 341 men with a median age of 55 years were operated for movement disorders (509), pain syndromes (52) or psychiatric disorders (24). The majority of patients underwent DBS (565), while a subset had radiofrequency lesioning procedures (20). Overall, in 361 patients surgery was performed with MER, and thereof in 12 patients an intracranial haemorrhage was detected (3,32%). The other 224 patients were operated without MER. Of these, 7 patients had intracranial haemorrhage (3,13%). In the MER group haemorrhage manifested as small haemorrhage at the target site (7), subdural haematoma (3) or ventricular bleeding (2). In the non-MER group haemorrhage was found as haematoma at the target site (4) or ventricular bleeding (3). Haemorrhage was asymptomatic in all patients except in 1 patient in the MER group, who had a persistent mild hemiparesis on the right side.

Conclusion: In this large patient series the use of MER with appropriate techniques did not significantly increase the risk of intracranial haemorrhage. Single unit recording can help to further define the target for DBS electrode placement or radiofrequency lesioning without incurring an additional risk for the patient.