Wrist and Hand Pain: Is it Carpal Tunnel Syndrome?
The purpose of this Blog is to help sort out painful problems of the wrist and hand, particularly of a neurologic nature, as well as for painful situations that may not have a clearly identifiable underlying cause or diagnosis. Pain in the wrist, hand, and fingers is a very common Chief Complaint for patient's seeing an Orthopedic Surgeon. These patients often come in with a preconceived diagnosis of Carpal Tunnel Syndrome as told to them by their Primary Care person, which may or may not be true, and may or may not be supported by good clinical information and testing. There are hundreds of reasons for patients to have pain in the wrists and hands of a musculoskeletal origin, but the focus of this Blog is as described.
Most of the neurologically based problems of the wrist and hand are Mononeuropathies from either a localized nerve irritation or an area of localized nerve compression. Pain of a neurologic origin is often subjectively described as burning, stinging, and usually more severe than a mild ache. There may be some throbbing. Other subjective symptoms include tingling/paresthesias and numbness (which is a subjective sense of loss of feeling). Other symptoms include weakness/loss of strength and clumsiness, with loss of dexterity involving the use of the thumb and fingers. The patient may state that they frequently lose control of objects and drop them.
From the standpoint of Anatomy, the three main nerves to the upper extremity are the Median, Ulnar, and Radial nerves. The Median Nerve is the most commonly affected of these, and the one that results in Carpal Tunnel Syndrome. The main area of sensation and feeling in the hand and fingers for the Median Nerve is the palmar side of the thumb, index, long, and usually the radial side of the ring finger. For practical purposes, there are no sensory areas on the back of the hand for the Median Nerve. From the motor or muscular aspect, the muscles of the thumb (thenar muscles) are the ones most affected, particularly the ability to abduct the thumb away from the palm (at 90° from the plane of the palm) by the Abductor Pollicis Brevis muscle, and the ability to abduct and rotate the thumb pulp/pad into opposition with the pulp/pad of the index and/or long fingers by the Opponens Pollicis muscle. In testing the strength and function of this muscle, the patient should be able to abduct and rotate the thumb in such a way the pulp/pad of the thumb touches the pulp/pad of the long finger, i.e. they should be “face-to-face.” Testing pinch strength should also be done in this position. Weakness and/or loss of function of this muscle results in the pulp/pad of the thumb resting against the radial side of the index or long finger, not the “face-to-face” position as described. These are the muscle activities that are tested during examination to identify Median Nerve based hand weakness.
The Ulnar Nerve has its area of sensory involvement on the palmar aspect of the hand, small finger, and the ulnar side of the ring finger, and also on the dorsum of the hand corresponding to the small and ring fingers. The muscles in the hand affected by the Ulnar Nerve are those of the Hypothenar area of the ulnar aspect of the hand and the Intrinsic Muscles for the fingers. Weakness of the ability to abduct the fingers away from each other, particularly the small finger away from the ring finger, indicate ulnar neuropathy. Also, weakness of the ability to adduct the thumb firmly to the radial side of the second metacarpal and base of the index finger is an indication of weakness of the Adductor Pollicis muscle. The particular test for this is Froman's test/sign in which the patient is asked to hold a piece of paper between the thumb and the second metacarpal and base of the index finger. The inability to hold it in place while the examiner tries to remove it indicates weakness of this muscle and is a positive test or sign. However, some patients may try to “cheat” by firmly flexing the tip of the thumb against the base of the index finger to hold the paper in place. In other words, they may have to “cheat” by using the long thumb flexor muscle (Flexor Pollicis Longus) to pinch and hold the paper in place. The examiner needs to watch for this when doing the examination.
The Radial Nerve, as it applies to the hand and fingers, has an area of sensation on the dorsum of the thumb, index, and long fingers and radial portion of the hand. However, within the hand there are no muscles that are activated by the radial nerve.
Sensation can be tested by several techniques to detect loss of feeling in the appropriate areas. These include testing for light touch with a cotton ball or a brush, sharp and dull discrimination using an open safety pin, 2 point discrimination, and monofilament testing. Using these various techniques helps define the degree or severity of the loss of feeling as well as the area or region of sensory loss, which should correlate with the nerve in question. However, when the nerve lesion is high enough in the arm, additional sensory or motor abnormalities may come into play, and will be further described when discussing the Mononeuropathies of the Upper Extremity.
Another aspect of the identification of the various neuropathies that can affect the upper extremity are electrical nerve testing in the form of Electromyography (EMG) and Nerve Conduction Studies (NCS). Nerve Conduction Studies evaluate the speed at which the nerve conducts electrical/nerve impulses. The slowing of nerve conduction indicates sensory neuropathy. The EMG tests the muscles for abnormal muscle impulses that would indicate motor neuropathy. The sensory complement of a peripheral nerve is more sensitive to the effects of compression than are the motor components of the nerve. As such, the symptoms of pain, paresthesias, or numbness reflect the damage to the sensory component of the nerve and account for the fact that these symptoms come on first. Identifiable muscular involvement such as measurable muscle weakness and atrophy indicate a problem of longer duration and greater severity of the neuropathy.
As with most neuropathies, there are varying degrees from mild to severe. The early or milder forms are generally manifested by the subjective sensory related complaints of pain and paresthesias, but not always easily confirmed on sensory examination, i.e. the symptoms may precede objective findings. As the neuropathy persists and worsens, then the subjective sensory complaints are more readily confirmed by objective sensory examination, and the motor aspect of the neuropathy may start to appear on examination. In the advanced and severe degrees, both the sensory and motor examination should be readily positive. The nerve studies as described could still be normal in the early and mild stages, but with time the sensory conduction delays should be identifiable, and in the late and severe stages both the nerve conduction and the muscular/motor testing will become identifiable in the EMGs.
Carpal Tunnel Syndrome (CTS) is the most common cause of wrist and hand pain with neurologic symptoms. It is the result of the Median Nerve being “compressed” as it passes from the wrist through the base of the palm (Carpal Tunnel) then on into the branches to the thumb and fingers. The point of compression is at the base of the palm where the Carpal Tunnel is located. Classic CTS should be easily diagnosed if all the sensory, motor, and supportive nerve studies are present. The pain and other sensory symptoms should be in the distribution of the median nerve as described. The symptoms may be intermittent or continuous. The symptoms are usually aggravated by manual activities and relieved to some extent by rest. Night symptoms are common, and typically the patient states that they awaken during the night with pain and tingling/numbness in their hand (“hand is asleep”) that causes them to wake up and either shake their hand out to wake it up, or hang it over the side of the bed. Although the symptoms tend to concentrate in the wrist &/or hand, the pain may sometimes migrate/radiate proximally back up the arm all the way to the shoulder. The patient may complain of weakness and/or clumsiness of the hand and fingers, and loss of dexterity. These symptoms can be a reflection of both the sensory and motor elements of this neuropathy. Objective examination for both the sensory and motor aspects of nerve function should help confirm/support the clinical diagnosis. In addition to the usual methods of testing sensation, there are “Provocative Tests” which are done to support the diagnosis. One is the Tinel’s Test, in which tapping (percussing) is done along the nerve as it passes from the wrist to the hand through the Carpal Tunnel segment. A positive test is when the patient experiences radiating pain and/or paresthesias out into the sensory distribution of the median nerve, most commonly into the index or long fingers as compared to the thumb. Phalen’s Test is done by holding the wrist and hand in sustained flexion, a position which tends to press upon the nerve at the Carpal Tunnel. When this position is sustained, a positive test is the worsening of the patient's sense of numbness &/or tingling, again in the Median Nerve distribution. The last is the Carpal Tunnel Compression Test, in which sustained and firm pressure is applied at the Carpal Tunnel at the base of the palm. As the pressure is applied and sustained, a positive test would be worsening/aggravation of the patient's symptoms. It might be noted that in very advanced and severe neuropathic situations these tests may not be positive. The nerve may be too damaged to respond to these tests. The nerve studies should also support the diagnosis. However, I have seen and treated patients with all the appropriate symptoms and complaints, and supported by abnormal sensory and motor examinations, that had normal sensory nerve conduction studies. Theoretically this is not supposed to happen according to the Neurologists or others doing the nerve studies, but I have seen it, and have successfully treated it surgically. In coding for Carpal Tunnel Syndrome in ICD-10, this is under the Code Set for Mononeuropathy of the Upper Limb, G56, which Excludes traumatic nerve injuries (S codes). G56.0 _ is the code for CTS, with the 5th Character of 1: Right, 2: Left, and 3: Bilateral.
As described above, if all of the "puzzle pieces” are present and fit together, the diagnosis should be straightforward. But sometimes all the "puzzle pieces” are not present, or they do not fit together in such a way as to make a clear picture, i.e. diagnosis. So what do you do then? There is a Code Set G56.1 for “Other" lesions of the Median Nerve. This would apply to all other non-traumatic affectations of the Median Nerve of the upper arm through the elbow and forearm, and within the hand and fingers, except for CTS. Depending on the location of the nerve lesion proximal to the wrist, i.e. most likely in the elbow or forearm region, many of the symptoms may mimic CTS. However, some of the sensory complaints may extend proximal to the wrist up into the forearm on the volar side. There may be some abnormal sensory findings proximal to the wrist. The muscles of the volar forearm work the wrist, hand, and fingers in flexion such that atrophy of these muscles &/or weakness of wrist and hand flexors (grip and pinch) should be identifiable on strength testing. Nerve studies should again help identify the level of the lesion. Tinel’s testing along the course of the nerve from the elbow and in the forearm may also help identify where the nerve lesion is. Within the hand, after the median nerve leaves the Carpal Tunnel, it branches into the digital branches to the thumb and fingers. The sensory examination and provocative testing such as Tinel's done in the palm or in the affected finger should help localize the lesion. It would also be possible that the motor branches of the median nerve beyond the Carpal Tunnel could be affected resulting in atrophy and/or weakness on thumb muscle strength testing. Nerve studies may or may not be helpful within the hand. The next most common Mononeuropathy of the upper extremity involves the Ulnar Nerve. The ICD-10 code is G56.2 : Ulnar Nerve lesions of the Upper Limb, which as described is specific and limited to Tardy Ulnar Palsy (also known as Ulnar Neuropathy at the Elbow). In this disorder, the Ulnar Nerve is irritated, damaged, or compressed as it passes behind and beyond the Medial Epicondyle of the humerus (the prominent knob on the inside of the elbow) and on into the forearm (Ulnar Groove or Tunnel). This is the “Crazy Bone” nerve. The symptoms of this disorder can be similar to those of CTS with pain, burning, stinging, tingling and paresthesias, and numbness, but should be isolated to the Ulnar Nerve aspect of the hand as described. The area of altered or abnormal sensation of the hand can be both on the palmar and dorsal aspect of the hand. When sufficiently advanced or severe, then the abnormal muscle exam as described should be present. When very advanced muscle involvement occurs, then the intrinsic muscles of the hand for the fingers are affected resulting in deformities of the fingers called “Clawing of the fingers.” The nerve studies should show a sensory conduction delay of the Ulnar Nerve along the course of the Ulnar Tunnel, and the EMGs will show abnormalities in the forearm and hand muscles when sufficiently advanced or severe.
There is another Ulnar Neuropathy that occurs in the upper extremity, but is at the level of the wrist and hand where the Ulnar Nerve enters the hand (Guyon's Canal). This can occur as an isolated disorder. The sensory neuritic symptoms can be very similar to Tardy Ulnar Palsy, but are restricted to the palmar side of the hand for the Ulnar Nerve as described, but not on the dorsal side. Consequently, any loss of sensation on the examination will be restricted/limited to the palmar side distribution of the Ulnar Nerve. The muscle or motor aspect on examination should be limited to those muscles within the hand as previously described. Because the nerve is rather deep and well protected in Guyon’s Canal, provocative testing such as Tinel’s may not be positive. However, nerve studies should help identify this lesion of the nerve at the hand. The problem with coding this by ICD-10 is that the Code Set G56.2 is limited/restricted as described to Tardy Ulnar Palsy, and does not appear to include this particular form of Ulnar Neuropathy. Therefore, I am not sure that I would use the code G56.2 for this particular diagnosis. There is G56.8 _: Other Specified Mononeuropathy of the Upper Limb, which I think would be the most specific and accurate for this diagnosis. (In ICD-10, this Code Set includes "Interdigital Neuroma” of the hand, a problem that I have never seen in 40 years of clinical practice.)
The third major peripheral nerve to the upper extremity and hand is the Radial Nerve, with the Code Set G56.3 for Radial Nerve Lesions of the Upper Limb. Compared to the Median and Ulnar Nerves, Radial Nerve problems are quite rare. However, the nerve can be compressed or irritated in the upper arm where it wraps around the humerus to the lateral side then enters the forearm crossing the anterolateral side of the elbow and into the dorsal forearm. As it passes into the dorsal forearm, it passes around the proximal radius (radial head and neck region). Although it is possible for non-traumatic lesions of the radial nerve to occur along the course of the nerve as described, most Radial Nerve lesions at these levels are the result of some traumatic event (Radial Nerve Palsy). In the distal forearm the Radial Nerve passes along the radial aspect of the distal radius then across the wrist and onto the dorsal aspect of the hand, thumb, index, and long fingers. The subjective sensory symptoms involve the Radial Nerve sensory area as described in the Anatomy. Tinel's testing along the nerve over the radial aspect of the distal forearm and the wrist is usually positive. Lesions at this level do not result in any identifiable muscle weakness. I'm not sure that nerve testing would serve much useful purpose for lesions at this level of the forearm, but would certainly be helpful for diagnosing lesions in the upper arm, elbow region, or proximal forearm. In my experience, Radial Neuritis in the distal forearm and wrist can be a non-traumatic disorder, but more often than not there has been some trauma to the area resulting in this lesion, even if it is no more than a local contusion. The ICD-10 code would be G56.3 for any and all non-traumatic lesions of the radial nerve from the upper arm through the forearm and wrist. There is nothing in the Code Set that is more specific.
Included in the Code Set G56: Mononeuropathies of the Upper Limb, is the Code G56.4 : Causalgia of the Upper Limb (Complex Regional Pain Syndrome II (CRPS II)). There are two types of CRPS, I and II, for both the upper and lower extremity. CRPS I, which in the past has been termed Reflex Sympathetic Dystrophy (RSD), is an Autonomic Nervous System disorder/dysfunction, which has no clear history of nerve trauma of any type. CRPS II, previously referred to as Causalgia, is also an Autonomic Nervous System disorder/dysfunction, which is related to a confirmed history of a nerve injury. For practical matters, the symptoms, complaints, and objective findings are virtually identical for both. Both of these disorders are usually the result of some sort of trauma or injury (distinguished from each other by the presence or absence of an identifiable nerve injury), but rarely can occur spontaneously, i.e. without prior trauma or injury. Needless to say, identification and coding of these disorders is confusing and difficult, if not nearly impossible. The Code Set G56.4 is limited to CRPS II, and Excludes(1) CRPS I (RSD of the upper extremity). The Code Set G90: Disorders of the Autonomic Nervous System, covers CRPS I for both the upper and lower extremities. Therefore, in order to use the G56.4 _ code for the upper extremity, there would have to have been an identifiable nerve injury. It might be added that patients with these disorders may very well be referred to Pain Management Specialists for care. As such, the G89 Code Set may come into play, either as an adjunct code to the primary diagnosis of CRPS I or II, since these problems usually occur subsequent to an injury, which includes surgery (a controlled form of “trauma”), or as the primary/first listed code for the Pain Management Specialist trying to manage the pain, not necessarily the underlying injury resulting in the CRPS.
Another “Neurologic" possibility for wrist and hand pain with sensory complaints that should be included in this Blog is Thoracic Outlet Syndrome (G54.0). The site of the nerve “compression" occurs in the neck and shoulder region, outside of the cervical spine and before getting into the upper arm. It can cause neuritic pain and tingling in the upper extremity out to and including the hand. The symptoms most often involve the ulnar part of the hand and small finger, but may be more generalized to the entire hand and all the fingers. It can mimic, and must be differentiated from, the Ulnar Nerve lesions as previously described. The symptoms and findings tend to be a little bit more generalized, vague, and nonspecific when compared to a true Mononeuropathy. The physical findings should help localize the problem to the neck and shoulder region with a variety of provocative tests. This disorder can also involve the vascular structures to and from the arm, but the neuritic form is most common. Nerve studies could be helpful in diagnosing this, but most likely would be negative, unless a sensory conduction delay could be demonstrated in the region of the Thoracic Outlet.
Last, but not least of the possible neurologic disorders affecting the hand and fingers, are Cervical Radiculitis and/or Radiculopathy from disorders of the cervical spine. These could result from spondylosis/arthritis and disc disorders. For these, I would refer you to the Blog on Neck Pain rather than discussing them again in this Blog.
There are some Polyneuropathies and Other Disorders of the Peripheral Nervous System (Code Sets G61. and G62.) that could affect the wrist, hand, and fingers. However these would most likely be systemic or generalized polyneuropathies of which involvement of the hand would be just a part of the problem, not the only manifestation.
What about patient’s with complaints of wrist and hand pain that do not fit any of the identifiable disorders already discussed? These would be patient's with pain, but without objective physical findings or other positive testing that would lead to a clearly identifiable diagnosis. There is Code R52: Pain, unspecified, but this is exactly that, “unspecified.” This code Excludes Site of Pain Codes such as M25.5: Pain in joint, which in this case the 5th Character would be 3 for the wrist, and 4 for the hand and fingers (added for 2017). However, this does not identify the disease causing the pain. If there is one, it should be identified and coded. There is also Code Set M79.6: Pain in the limb, including the hand. However, this Excludes(2) joint pain (M25.5 _). In this Code Set M79: Other Soft Tissue Disorders, not elsewhere classified, is M79.63 for pain in the forearm, and M79.64 for pain in the hand and fingers. These codes would tend to cover a limited regional pain for the wrist, hand, and fingers for which there was no other diagnosable disorder that could be coded.
There are a multitude of M Codes for Musculoskeletal Diseases that could cause wrist and hand pain, and which a diagnosis could be identified and coded. I have not included these in this Blog as it would take forever to go through all of them. As stated in the introduction, this Blog is oriented towards neuropathic disorders or otherwise “undiagnosable” pain in the wrist, hand, and fingers.
Posted in Coding Blogs on Oct 20, 2016