Should ultrasound be the diagnostic test of choice or used interchangeably with nerve conduction studies in the diagnosis of CTS?
Ultrasound has been a tool in search of business as far as I can discern. The only nerve in the body where the ultrasound has seemingly been useful for a diagnosis of entrapment is that of carpal tunnel syndrome. There have been a number of public articles in the medical journals in the past 10 years related to trying to define the potential benefit of ultrasound and the diagnosis of carpal tunnel syndrome and delineating the changes in median nerve size from pressure on the median nerve at the carpal tunnel and subsequent decrease in the size postoperatively. There is extreme patient bias exhibited in those that undergo surgery such as in the article by Smidt and Visser from the Netherlands published in Muscle and Nerve, August 2008, Volume 38, pages 97-101, wherein they were trying to determine the value of postoperative sonogram and the correlation between sonography and the clinical outcome after surgery. Though they initially started with a group of 172 patients, only 88 of them underwent surgery! Additionally, the mean time of symptoms of the patients prior to surgery was a year. Americans generally want results yesterday. They don’t want to wait forever for treatment and, as pointed out in my previous blog, early intervention tends to yield better results overall. Additionally, as Smidt and Visser point out with their limited study which is larger patient volume than the prior publications, “from the available data we conclude that sonography of the median nerve cannot be used to assess whether re-exploration of the carpal tunnel is needed in an individual patient with poor outcome after surgery”. It is particularly important because in their series there were a high percentage of unsatisfied patients. In fact, of the 79 patients that they operated on only 56%, i.e. 44, reported complete recovery or much improvement; 3% reported no change and 12% reported worsening of their symptoms, i.e. bad results in 15% and only excellent results in 56%. This compares unfavorably with the published results for ECTR and in my personal experience with over 5,000 procedures. Indirectly their article supports the application of endoscopic over open carpal tunnel release and early treatment rather than late. It certainly does not support the use of sonography in the evaluation of carpal tunnel patients given the overall inferior results that they had to offer in their patients treated.
Ad sonography to the same junk pile that the Neurometrix NC-Stat on-call belongs in, i.e. worthless.