Electrodiagnosis and pathophysiology in amyotrophic lateral sclerosis
Amyotrophic lateral sclerosis (ALS) is a fatal neurological disease with degeneration of upper and lower motor neurons. The neurophysiological examination is an essential supplement to the clinical examination in order to confirm or exclude the diagnosis of ALS.
Our research focuses on optimising the diagnosis of ALS by developing and refining the electrodiagnostic techniques, improving the diagnostic criteria, and increasing our understanding of the pathophysiology behind ALS, and exploring prognostic factors. Furthermore, techniques for objective monitoring of disease progress are studied Much of the research is carried out in a multicentric and multidisciplinary approach.
The currently on-going studies described below is partly build on the experience and knowlodge from previous projects at the department investigating sensory involvement in ALS (Pugdahl et al., 2007; Pugdahl et al., 2008; Isak et al., 2016a; Isak et al., 2017; Isak et al., 2016b), electrophysiological markers for upper motor neuron degeneration (Furtula et al., 2013b), techniques for monitoring lower motor neuron loss (Furtula et al., 2013a; Jacobsen et al., 2017), variation in the examination among European neurophysiologists (Pugdahl et al., 2010), spontaneous activity in the tongue (Tankisi et al., 2013), ultrasound in detecting fasciculations (Johansson et al., 2017), and evaluation of electrodiagnostic criteria for the diagnosis of ALS in a large multicentre trial (Johnsen et al., 2017).
Excitability properties in ALS – from brain to muscle
Excitability studies covering all parts of the nervous system are performed in ALS patients in a prospective multicentre study following the patients over time. The techniques include threshold-tracking for axonal excitability, jitter for synaptic excitability, muscle velocity recovery cycle (MRVC) for muscle fibre excitability, and transcranial magnetic stimulation with threshold-tracking (TT-TMS). In addition repetitive TMS (rTMS) may be applied as treatment of ALS.
Diagnosis and follow-up
Peak-ratio technique: The diagnostic value of the peak-ratio (PR) technique for quantitative evaluation of the interference pattern is investigated in different muscles. The technique has a great potential in supplementing the quantitative motor unit potential (MUP) in establishing an early diagnosis of ALS.
MScanFIT MUNE: A new promising method for monitoring loss of motor units called "MScanFIT MUNE" is evaluated with respect to reproducibility and diagnostic and prognostic potential in ALS in comparison to the more traditional motor unit number estimation (MUNE) methods, motor unit number index (MUNIX) and multiple point stimulation (MPS) MUNE.
Birger Johnsen, MD, PhD firstname.lastname@example.org
Hatice Tankisi, MD, PhD email@example.com
Kirsten Pugdahl, MSc, PhD firstname.lastname@example.org
Anders Fuglsang-Frederiksen, MD, professor, DMSc email@example.com