Neurotron, Incorporated

   Innovative Medical Technology

                 Established 1981

Neurometer^® Clinical Endocrinology & Diabetes Applications

  Endocrinologists use the painless, non-invasive sNCT electrodiagnostic examination procedure to evaluate metabolic polyneuropathies commonly observed in clinical endocrinology.  Annual sNCT evaluations for patients at risk for polyneuropathy (e.g. diabetes, hypothyroidism) are recommended to objectively assess the presence or absence of a polyneuropathy or evaluate its progression. Particular concern is given to evaluating protective sensation. Normal sNCT evaluation results indicate that no further sNCT testing beyond an annual exam is necessary unless a change in the clinical condition suggesting sensory dysfunction warrants a repeat evaluation.

Patients with certain types of endocrine disorders (e.g. diabetes) are susceptible to developing compressive neuropathies and radiculopathies and testing for these conditions may be required based upon the clinical impression that the differential diagnosis of a patient's sensory impairment may includes these conditions.

The sNCT procedure had its origins in the evaluation of diabetic patients at the Johns Hopkins University School of Medicine, Department of Neurology beginning in the early 1980's. This clinical research led the FDA to grant permission to market the Neurometer CPT device in 1986. Presently, there are more than 700 peer reviewed articles demonstrating clinical utility of the sNCT evaluation.  Approximately 20% of these papers are devoted to diabetes.

The sNCT is the only electrodiagnostic sensory evaluation able to quantify both hyperesthesia and hypoesthesia. Hyperesthetic conditions reflect inflamed or irritated sensory nerve fibers that have not yet lost their functioning but have abnormally low electrical excitatory response thresholds. Hypoesthesia, differs in that it is associated with a more advanced stage of neuropathy and represents a loss of function. Hyperesthesia occurs before hypoesthesia in progressive peripheral nerve damage.  Detection of hyperesthesia permits earlier therapeutic intervention, thereby improving the prognosis with the potential of limiting more severe damage and reducing the cost of care. Publications demonstrate the sNCT evaluation ability to detect and evaluate hyperesthesia in 50% of the neurologically asymptomatic diabetic subjects as well as non-diabetic obese individuals. Studies shows that in those diabetics with clinical signs of neuropathy about 75% of the abnormalities were hyperesthetic. Diabetics with foot ulcerations, in contrast,  had more than 98% of their measures hypoesthetic.

The sNCT evaluation is also the only electrodiagnostic procedure capable of selectively evaluating the functional integrity of the large myelinated, small myelinated and unmyelinated sensory nerve fibers. This is particularly important for diabetic subjects because diabetic neuropathy is not selective for a specific sub-population of sensory nerve fibers. For instance, the sNCT evaluation can detect small unmyelinated fiber neuropathy in diabetic subjects who have normal myelinated fiber function. Numerous studies have demonstrated that the sNCT evaluation is able to selectively evaluate small fiber function while the other neurodiagnostic tests such as the Nerve Conduction Velocity (NCV) lack this ability.

Small fiber functioning represents protective sensation. Protective sensation is extremely important because it is the loss of protective sensation that can lead to "painless neuropathy" and amputation. Small unmyelinated fiber function is also correlated with autonomic nerve integrity. Autonomic neuropathy is responsible for the majority of deaths occurring among diabetic patients and the ability to easily assess unmyelinated nerve function with the sNCT evaluation allows early identification of those patients at risk for related cardiac complications.

The sNCT evaluation is the only electrodiagnostic procedure which can test at the tips of the toes and fingers where the distal axonal neuropathies commonly begin in diabetics. This allows the sNCT evaluation to detect diabetic neuropathy months or years before it would be detectable by other procedures such as the sensory Nerve Conduction Velocity (NCV) exam or Skin Punch Biopsy (SPB). The tuning fork evaluation is not capable of selectively assessing large fiber function in the tip of the great toe because vibration is conducted by bone conduction proximally and the loss of sensation can not be isolated to a specific location. Also, unmyelinated fibers can be polymodal and respond to a mechanical stimulus such as vibration, mono-filament pressure or pin-prick. As a consequence, patients with a selective loss of large fiber function may show up normal with these evaluations.
 

Another type of polyneuropathy reported to occurs in diabetes is immune mediated. This type of polyneuropathy presents with an asymmetric distribution of sensory dysfunction which can occur anywhere but typically occurs around the dorsal root ganglia. The sensory NCV evaluation is limited to testing the physiological integrity of the peripheral distal segment of nerves, and diabetic patients with proximal immune mediated lesions of peripheral sensory nerves have normal peripheral sensory NCVs. Studies from Columbia University, New York Medical College and St. Vincents Medical Center in New York, University of Louisville School of Medicine and the United States Air Force, have documented the ability of the sNCT evaluation to detect and quantify these proximal demyelinating polyneuropathies.

Diabetics may also suffer from a vascular or circulatory related peripheral neuropathy. These neuropathies may be focal and can effect sensory function anywhere on the body. The sNCT evaluation is unique because it can be used to test any cutaneous body site which allows the clinician to objectively quantify this condition.

One additional and important consideration about the sNCT evaluation is that it is painless. This feature encourages far better patient compliance for repeated evaluation than the painful NCV or SPB. The painless nature of the sNCT procedure is also of particular value in enhancing compliance for the electrodiagnostic analysis of juvenile diabetic patients.

Endocrinologists primarily use sNCT/CPT studies to objectively evaluate the impact of diabetic and pre-diabetic conditions to monitor and guide their patient’s medical management. The Neurometer® CPT evaluation is prescribed by the endocrinologist when clinical examination findings are equivocal or suggest the development of an impairment in distal sensory function and an objective evaluation is required to confirm and evaluate a diagnosis of polyneuropathy. Typically, the distal great toe test site is tested bilaterally and if a polyneuropathy is detected then therapeutic interventions or modifications are considered to attempt to reverse the condition and/or prevent its progression. Normal CPT evaluation results indicate that no further CPT testing is necessary unless a change in the clinical condition or laboratory findings suggesting sensory dysfunction requires an evaluation.

 

See related Publications.