Axonal excitability testing using threshold tracking technique (Figure 1) provides complementary information to conventional nerve conduction studies. Axonal excitability testing may be used to infer the activity of a variety of ion channels, energy-dependent pumps and ion exchange processes activated during the process of impulse conduction. The method has been developed by Professor Hugh Bostock, Queen Square, London, United Kingdom. The software is called Qtrac and the method has recently been adapted to muscle membrane (Figure 2) and cortical excitability and a novel motor unit number estimation (MUNE) method, so-called MScanFit MUNE (MScan) (Figure 3). MScan is a promising technique for assessing motor unit loss. Reliable detection of motor unit loss is important in diagnosing and monitoring disease progression in neuromuscular disorders, in particular amyotrophic lateral sclerosis (ALS). For this, the MUNE techniques, being non-invasive electrophysiological methods for estimating the number of functioning motor units in a muscle, are valuable tools. MScan, unlike most other MUNE methods in use, assesses all the motor units in a muscle by fitting a model to a detailed stimulus-response curve, and is fast and simple to perform which is suitable for both research and clinical use.
All the above mentioned methods were established at the Department of Neurophysiology, Aarhus University Hospital in 2015 in close collaboration with Professor Hugh Bostock. Different aspects of Qtrac are being used in several PhD and research year projects for understanding disease pathophysiology as well as earlier and more accurate diagnosis of amyotrophic lateral sclerosis, spinal cord injury, epilepsy, chemotheraphy-induced neuropathy and diabetic neuropathy.
Hatice Tankisi, Associate Professor, Consultant, PhD, email@example.com