Why Your Hand Pain May Not Always be "Carpal Tunnel"

By: Dr. Steven Scappaticci, B.Sc. (Hons.), CSCS, DC

“Where you think it is, it ain’t” – Ida Rolf
 
            A patient presents to your office with tingling into their right hand. They have spoken to a co-worker that had a similar complaint and after a quick Google search, they are convinced it is Carpal Tunnel Syndrome.
            You understand where they are coming from, but given the complexity of the surrounding structures, you highlight the importance of a thorough physical examination to rule in or out other possible diagnoses.
            Speaking of other diagnoses, when it comes to “hand tingling” there can be a long list of differential diagnoses. The more common differentials include: Carpal Tunnel Syndrome, Pronator Teres Syndrome, Anterior Interosseous Syndrome, Thoracic Outlet Syndrome, Brachial Plexopathy, Cervical Radiculopathy (C6), Diabetic Neuropathy, Ulnar/Radial Neuropathy, Fracture, Tumor/Cyst. The list goes on and on.
            To help narrow down the list of differential diagnoses, a proper history and physical exam are imperative. The patient is a carpenter and tells you that for the last few weeks they have been working many more hours than usual in order to prepare for the holiday season. Their hand complaint is located closer to the thumb and index finger. They find that by midday, they can barely use their screwdriver anymore as the symptoms flare up. (Note: No trauma has been sustained and the patient is otherwise healthy)     
            As you are progressing through the physical exam you note that there is a significant amount of tenderness over the proximal anteromedial aspect of the right forearm. You ask the patient to resist you moving their wrist/forearm and find that there is moderate weakness as you test their ability to pronate (Note: They are able to make the “OK” sign (Pinch Test) with their thumb and index finger with adequate strength). Continued palpation of the pronator teres reproduces their chief complaint. Given the motor and sensory deficits, lack of cervical spine (neck findings), unremarkable health history, and no trauma, you are lead to a diagnosis of Pronator Teres Syndrome. (Note: Tinel’s at the Carpal Tunnel and Guyon’s Cannal were both unremarkable)  
 
            Now this is a fictional and simplistic (although entirely possible) presentation, however the purpose of this was to highlight the importance of differential diagnoses, as well as a thorough history and physical examination.   
            Human anatomy is complex and never as neat as it appears in textbooks. Lets remember that the nerves that supply our shoulders, arms, and hands all stem from our necks, thus one may need to examine along the course of a whole nerve/limb to find the true source of the issue.
            In this particular case, it was the median nerve that was affected, specifically within the two heads of the pronator teres. The median nerve however, arises from the lateral and medial cords of the brachial plexus (thus injury to either one of these can lead to potential symptoms) and enters the axilla (armpit). It continues downwards between 2 muscles (biceps brachii and brachialis) until it crosses the cubital fossa (elbow). The median nerve passes between the heads of the pronator teres as mentioned earlier before travelling between even more forearm muscles and dividing to supply the rest of the forearm and hand.
            If the practitioner in this example had agreed with the patient right off the bat (unlikely) or if they had only focused on the median nerve at the carpal tunnel, it could have potentially lead them down the wrong path with the wrong diagnosis and would have wasted the patient’s time. This emphasizes the quote below that I will end this post with.
   
“Specificity of Assessment = Specificity of Treatment = Specificity of Results”
 Dr. John Saratsiotis
 
(Note: the listing of all specific history findings and orthopedic tests were purposely omitted for this post, as to not give the diagnosis away early on in the blog)