Clinical Article Thermography - a valuable tool to test hydrocephalus shunt patency

Summary Introduction. Shunt-function in hydrocephalic patients is verified by clinical examination and repeated cranial computed tomography (CCT) in most cases. Because of the disadvantages of multiple radiation espe- cially in children it was our aim to introduce video-thermography as a simple and non-invasive methodology to evaluate shunt function. Methods. 54 patients treated with shunts for hydrocephalus were tested. A ventriculo-peritoneal shunt had been implanted in 38 patients, a ventriculo-atrial shunt in 16 patients. Recent CCT-scans were available for all patients and served as control. None of the patients presented with clinical signs of shunt-dysfunction. The temperature of the skin covering the drainage catheter distal to the valve was recorded real-time by a calibrated infrared camera. After cooling the skin area downstream of the valve for exactly 1 min with an ice pack, changes of the skin temperature in the area downstream were registered by a thermocamera. The signals were transferred to a video screen and recorded on video- tape. By off-line analysis of the obtained pseudo colour images varia- tions of 0.1 � C in skin temperature could be measured. Results. Temperature distribution of the area under investigation revealed a significant reduction of the skin temperature according to the location of the downstream catheter segment in 48 patients after cooling. In 6 patients skin temperature remained constant, although clinical evaluation and CCT-scan showed no signs of shunt dysfunction. Shunt patency could be verified in more than 85% of the patients by thermal imaging. Conclusion. Infrared-thermography is a valuable and promising tool for replacing CCT-scanning as a screening method to test shunt function in hydrocephalic patients.