Can Handheld NCS Devices Lead to Earlier Diagnosis?

Handheld NCS electrodiagnostic devices offer a faster and more effective way for clinicians to identify the presence of Carpal Tunnel Syndrome

TIME IS money when it comes to healthcare. Demand is booming and resources are limited, so anything that services can do to reduce waiting times will be invaluable. However, although early identification may be crucial, it can also be difficult. There is no gold standard to refer to and clinicians will rely on their observations and information they have about a patient’s medical history. Patients may present in various ways and respond differently to treatment regimes.

Current Diagnosis Methods

Clinicians will adopt a number of methods when assessing the needs of patients based on a physical examination, medical histories and screening tests. These include:
• Phalen Test: This involves flexing the wrist for 60 seconds. If the patient experiences paraesthesia or pain in the median nerve it will be considered positive.
• Tinel Tests: A clinician will lightly tap over the median nerve. If Carpal Tunnel Syndrome is present this may result in a shooting pain.
• Durkin Test: This relies on compression of the underlying median nerve. Thumbs are placed on the proximal edge of the nerve to recreate the symptoms of Carpal Tunnel Syndrome.

Each of these is affordable and simple to perform but they are prone to misdiagnosis. The literature review puts the sensitivity of the Phalen test at between 67% to 83% and 40% and 98%. The Tinel test is rated at between 48% and 73% 16 . It’s a wide range which makes it difficult to make a clear diagnosis. Other conditions may present some or all of the symptoms without being Carpal Tunnel Syndrome. Equally it is possible not to have some of the symptoms and still have Carpal Tunnel Syndrome.

Electro Diagnostics

When results are uncertain doctors will move on to electro diagnostics testing which uses nerve conduction studies (NCS) and electromyography (EMG) testing. However, to avoid misdiagnosis, clinicians should consider using these tests to confirm or eliminate the presence of Carpal Tunnel Syndrome.

NCS evaluates how fast electrical signals move through the median nerve in the carpal tunnel and into the muscles. It’s a bit like measuring the flow of water through a garden hose. If this is slowing for any reason it suggests there might be a block or a kink in the hose somewhere down the line. It is this reduction in the flow of electrical signals that leads to altered sensations and muscle weakness.

However, this may not be enough on its own to confirm or eliminate the existence of Carpal Tunnel Syndrome. Clinicians will often use EMG tests alongside NCS. These monitor the muscle itself rather than the nerve by examining how it depolarises when activated. It can be used in two ways. The least invasive approach is to place electrodes on the skin to stimulate the muscle and record its response. Alternatively, some tests may use a small needle which is inserted into the muscle and is used to provide the stimulation. However, this process can be painful.

The advantage of EMG is that it can identify a very subtle loss of muscle function long before the patient experiences any subjective loss of strength. Therefore, when other symptoms are not present, this can highlight a problem which might have gone undetected. It plays a very important role in identifying nerve damage in the earliest stages and enabling prompt and timely treatment.

Next Generation Tests

EMG and NCS tests play an important role in the diagnosis process. They can provide certainty when previous assessments have been inconclusive, and they can help clinicians determine which courses of treatment will be most effective for individual patients. However, they can be expensive with machines costing more than $10,000 and can take time. For health services looking to cut costs and improve turnaround times, that can be a big turn off.

A new generation of point of care (POC) handheld NCS devices is now coming to market which offer a faster and more affordable alternative.