Carpal Tunnel Syndrome

 

 General:  Carpal Tunnel Syndrome (CTS) is a leading cause of disability and found in 10% of Americans.  It is an entrapment neuropathy wherein the main sensory nerve of the hand, the Median Nerve, is compressed and irritated at the wrist.  The Median Nerve is normally wrapped in a tight, elastic band (the flexor retinaculm) in a boney tunnel formed by the carpal (wrist) bones.  CTS is found more often in persons with a small tunnel and women generally have smaller tunnels than men and that is why they get it three times as often.

Symptoms:  Common initial symptoms are numbness, “pins and needles”, tingling, a dead sensation, and a lack of feeling which is usually in the fingers and hand.  Some patients can localize the symptoms to be worse or only present in the median innervated digits (thumb, index, middle finger, median half of the ring finger).  Others can’t do this.  Sometimes the numbness seems to be in the wrist, forearm, or upper arm.  Tingling is a sensory fiber symptom and the brain can usually localize where this is coming from pretty well.  Numbness or pain may worsen while using the involved hand especially in gripping something or bending the wrist. The hand may get numb at night, awakening the patient, or while performing some job with their hand, such as writing, driving, typing, using the mouse, or a hair dryer.  The patient may find their arm is only comfortable when lying straight out at their side in bed, but not in their lap, or above their head.  The patient may have to go through elaborate arm positioning in bed before they go to sleep so their hand doesn’t bother them during the night.  Pain is typically aching, burning, or throbbing.  Pain is usually poorly localized by the brain and the patient may only be able to say the pain is in the right arm, or the shoulder, even.  The pain typically bothers the patient at night and then, may be excruciating, even preventing sleep.  Pain located in the shoulder may confuse the patient and the physician, resulting in investigations such as an MRI scan of the neck looking for a herniated disc, when the problem is actually in the wrist.  Some patients complain of weakness in the hand.  The patient may have trouble with simple hand movements such as hair brushing or holding a fork.  They may accidentally drop objects due to reduced pinched strength between the thumb and first finger while doing simple tasks such as opening a jar or using a screwdriver. This is usually weakness involving grip of the fingers or thumb, for acts such as holding a glass, or a heavy pan between the thumb and flexor fingers.  Late in CTS there may be atrophy (wasting, or lack of bulk) of the muscles at the base of the thumb.  Non-neurologic symptoms may occur also, such as swelling or redness of the hands, dryness, and changes in nail growth.

Associated Medical Issues:  CTS is considered to be genetic and due to a small tunnel but other conditions such as wrist fracture and subsequent scarring may also damage the nerve.  There is an epidemic in typists, 10 key operators, mouse users, assemblers, cashiers, secretaries, bookkeepers, welders and cutters, electrical equipment assemblers, janitors and cleaners, bank tellers, and CRT data processors.  It occurs in musicians (guitarists, pianists, violinists), atheletes (tennis players, gymnasts, weight lifters, bicyclers, motorcycle riders), seamstresses,  barbers, hair stylists, butchers, house cleaners, and gardeners.  Meat packers and airline assembly workers have very high rates of carpal tunnel syndrome.  Workers who use power tools or vibrating electrical equipment have very high rates of carpal tunnel syndrome and this includes jackhammer operators. People who cook, knit, sew, do needlepoint, do carpentry, or play computer games get CTS. The symptoms may be set off by a weekend of painting the garage, working in the yard, or writing letters.  CTS occurs seasonally as people use their hands–women at Christmas wrapping presents and writing Christmas cards, students, cramming for final exams in January or May, accountants at April 15th, business employees who input data or manually write end of the month, end of the quarter, or end of the year reports.

CTS also occurs in association with many medical diseases–diabetes, obesity, rheumatoid arthritis, alcoholism, the final trimester of pregnancy, hypothyroidism, acromegaly, multiple myeloma, tuberculosis, amyloidosis, gout.  CTS may be caused by previous fracture of the wrist (Colle’s fracture) and then is usually a more severe neuropathy which usually requires surgical release.  Tumors or growths at the wrist such as ganglions may cause CTS.

Course:  The course of CTS varies from very mild cases with a normal neurologic exam and a normal EMG to chronic, severe cases lasting over 20 years with anesthesia in the median innervated fingers of the palm and atrophy of the base of the thumb.  It may bother someone for a year and then go away, only to return 10 years later when some unusual activity provokes the symptoms.

Differential Diagnosis:  Cervical Radiculopathy (a pinched nerve in the neck), Brachial Plexus Problem, Spinal Cord, or even Brain Disease such as a stroke or MS.

Physical Exam:  The neurologic exam may be normal, or may show irritability over the median nerve when tapped at the wrist (Tinel’s sign), or numbness of the hand from a sustained flexion or extension posture (Phalen’s maneuver).  The patient may have sensory loss in the palmar fingers innervated by the median nerve (usually the thumb, index, middle, and one half of the ring finger).  There also may be wasting or weakness of  the muscles at the base of the thumb.

Testing:  The main test that shows what is wrong is the Electromyogram or EMG.  This is an outpatient, office procedure which is mildly uncomfortable.  The test has two parts.  The first involves shocking different peripheral nerves and studying how they transmit electricity (Nerve Conduction Studies-NCS).  The second part involves inserting a small needle into muscles of the hand, forearm, upper arm, shoulder, and neck.  This test can make the diagnosis of CTS, and specify whether the motor or sensory branch of the median nerve, or the branch of the nerve to the muscle is involved.  Other tests that may be done, but may be normal are:  plain X-Ray of the wrist or cervical spine, CAT scan or MRI scan of the cervical spine, and blood work.  Ten percent of patients with carpal tunnel syndrome may have a normal EMG and this is especially true with symptoms which have only been present a few months and a normal neurologic exam.

Treatment: A) Rest: The first idea here is resting the hand.  The patient should be encouraged to think about how they use their hands in their daily routine.  They should avoid flexion/extension movements or sustained bent postures of the wrist that may aggravate the symptoms.  This idea sounds simple, but it is difficult to do.  However, it is very important.  Persons that make their living with their hands and also have CTS can’t rest the hand well and this makes their treatment more difficult.  A shorter history, younger age, unilateral symptoms, and a negative phalen sign are predictive of better outcomes.

B) Medication.  Traditionally Nonsteroidal Anti-inflammatory medications (NSAIDs) such as Alleve or Advil have been prescribed for their pain killing or analgesic activity.   CTS is not an inflammatory condition.  However, CTS in not an inflammatory condition and a drug that works on neurogenic pain, such as Neurontin (gabapentin) may give some relief.   Short doses of oral cortisone, like Medrol dosepack or a week of prednisone  are reported to provide brief, but not long lasting therapy.

C) Splinting.  Splinting the hand in a neutral position at night or sometimes during daily activities works for CTS. This involves wearing a loose fitting splint which immobilizes the wrist.  Splints may be purchased all over the metroplex, commonly in drugstores.  The purpose of the splint is to hold the wrist in a neutral position, so it need not be tight.  Common splints are made of cotton fabric with metal stays and Velcro snaps.  They should go on like a glove and immobilize the wrist.  Splinting at night helps when the hand gets bent in flexed positions.  Splinting may help significantly after just a few days.  Many persons with mild Carpal Tunnel Syndrome wear their splints for just a few nights or a few weeks when their symptoms trouble them, after some activity such as painting the garage or clipping the weeds in the yard.  The splints should be used for several weeks or months depending on the severity of the problem.

D) Cortisone Injection.  This involves injection of cortisone by a small needle through the skin at the wrist, the transverse carpal ligament, and directly into the tunnel.  Cortisone injection can shrink swollen tissues and relieve pressure on the nerve.  It may give relief in more than 75% of CTS patients but the injection hurts when it is given and there may be a transient increase in pain for a day or two after the injection.  Wrist carpal tunnel injections may cause overlying skin change,Unfortunately, in many cases, the relief is temporary and in that situation, the injection may be repeated, usually at monthly intervals for up to a total of three injections.  The injection is like getting a shot of cortisone for tennis elbow or bursitis and is usually no big deal.  The wrist injection doesn’t have generalized or systemic effect.  Sometimes during the injection if the needle lies too near the nerve, the patient may experience transient symptoms.  Repositioning of the needle during the injection will avoid this.

E) Surgical release.  Following all of these treatments, if symptoms persist, then the patient may require surgery.  Surgery for Carpal Tunnel Syndrome may provide a cure for 81% of patients, 10% of patients with improvement, and 9% who did not benefit (some unchanged, others worse.)  The success rate of surgery performed on purely clinical grounds in the presence of normal nerve conduction studies (NCS) is noticeably lower than that of similar operations performed when NCS are abnormal.  Surgery can be done with an open release or via a small endoscopic procedure.  The most common surgical error is failure to completely divide the transverse carpal ligament which is more common with the endoscopic approach due to lack of complete visualization of the ligament.  Postoperative pain is slightly more frequent with the open approach.  After successful decompression that relieved symptoms for some time, true recurrence of CTS is a rare event.

Surgery is more effective for patients with moderate to severe carpal tunnel syndrome, those over age 50, those with symptoms of 10 months or longer, those with continual numbness, and those with thumb base atrophy.  It is the treatment of choice for patients with post fracture, polyneuropathy, or arthritic induced nerve damage.  It is also the only treatment that will allow some patients to return to work at a job that requires continual stress of the median nerve in the carpal tunnel.  One lay misperception regarding Carpal Tunnel Syndrome is that if you have it, then you automatically need surgical treatment.  The patient should progress through conservative management to surgery as the last resort unless he presents with clinical or EMG findings of severe disease.

 

BTD 070815

 

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