Failed carpal tunnel surgery

by Nathan Wei, MD, FACP, FACR

Nathan Wei is a nationally known board-certified rheumatologist and author of the Second Opinion Arthritis Treatment Kit. It's available exclusively at this website... not available in stores.

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There are multiple reasons for the failure of surgery to make carpal tunnel syndrome better. The first is the automatic assumption that overuse is the underlying cause of the syndrome without a careful and thoughtful approach to the diagnosis of other underlying conditions.

It is important to seek evidence of conditions known to be associated with CTS such as obesity, diabetes mellitus, thyroid disease, connective tissue disorders such as rheumatoid arthritis, osteoarthritis, inflammatory back pain, psoriasis, gout, and inflammatory bowel disease. Ask about any symptoms that could point to an inflammatory or metabolic illness, such as unusual fatigue, fever, night sweats, hair loss, sun sensitivity, skin rashes, eye inflammation, Raynaud's phenomenon, or unexplained changes in weight.

An evaluation for a true arthropathy or diffuse peripheral neuropathy should be done. This includes symptoms such as prolonged morning stiffness, true swelling of joints or soft tissues, musculoskeletal pain remote from the hands, paresthesias outside the median nerve distribution of the hands or involving the lower extremities. Ask whether the patient ever has undergone carpal tunnel surgery that failed to relieve symptoms. Finally, consider pregnancy. About 20% of pregnant women describe paresthesias that are due to CTS stemming from fluid retention, generally begin in the third trimester and resolve spontaneously following delivery.

On physical exam, check for signs of inflammation such as swelling, erythema, and crepitus. These are seldom seen in patients with true overuse syndromes, and their presence is cause for suspicion. Similarly, check for joint pain or limited movement in the lower extremities, pain radiating from the spine, or widespread tenderness in periarticular tissues. Neurologic abnormalities outside the median nerve distribution of the hands would be unusual, as noted. Examine the patient's skin for evidence of Raynaud's phenomenon, livedo reticularis, or psoriasiform lesions.

The most common reasons for misdiagnosis of CTS is weakness in the annular ligament of the elbow, or referred pain from the cervical vertebrae to the thumb, index and middle fingers. A problematic annular ligament when pressed may be a trigger point to the carpal tunnel distribution in the hand. Once the annular ligament is treated (usually with injection), it is often deactivated and the symptoms of carpal tunnel syndrome disappear.

Look for radiologic evidence of osteoarthritis (joint space narrowing with sclerosis, osteophytes, subchondral cysts) or inflammatory wrist involvement (juxta-articular osteoporosis, narrowing, erosions, soft-tissue calcification). Magnetic resonance imaging is recommended for more precise evaluation of carpal tunnel anatomy--for example, to identify anomalies of the median artery or local muscles such as the palmaris longus--or to rule out a space-occupying lesion (e.g., ganglia, hemangiomas, lipomas).

Laboratory studies are an essential part of the evaluation of any patient who presents with CTS. Test results suggestive of metabolic disorders include hyperglycemia, an abnormal TSH level, hypercalcemia, abnormal liver function studies, or renal insufficiency. Inflammatory processes are suggested by anemia, abnormal platelet count, leukopenia, elevated sedimentation rate, increased C-reactive protein level, and positive rheumatoid factor or antinuclear antibody tests.

Nerve conduction studies may be useful in difficult cases with confusing signs and symptoms. They are an essential part of the presurgical evaluation. An EMG may be ordered to check for nerve problems occurring at the elbow or in the neck.

Initially, patient discomfort may be alleviated with simple measures such as nocturnal wrist splints and judicious use of nonsteroidal anti-inflammatory agents. Local corticosteroid injections can relieve pain and numbness and, in patients with recent-onset disease and no significant muscle atrophy, may eliminate the need for surgery. However, studies suggest that pain and other symptoms return within six months of injection in about 50% of patients.

Treatment of an underlying metabolic or inflammatory disease may alleviate CTS manifestations, as in the case described. However, patients with concurrent joint-space narrowing caused by arthritis or chronic tenosynovitis may continue to experience discomfort and should be considered candidates for carpal tunnel release if conventional measures fail. In patients with a persistent median nerve deficit but no evidence of systemic illness, surgery--whether by the traditional open approach or endoscopic release--has a high cure rate.

For patients who fail surgery, an MRI may help point to the reason why. In addition to incomplete release of the flexor retinaculum, postoperative MRI changes in failed carpal tunnel surgery include excessive fat within the carpal tunnel, neuromas, scarring, and persistent neuritis.

A newer technique, called ultrasound-guided percutaneous needle release is a minimally invasive method for carpal tunnel release and may may make surgical approaches, whether endoscopic or open, obsolete.

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