1. Muscle ultrasound as a diagnostic tool in
amyotrophic lateral sclerosis
– comparison with electromyography
Alexander Grimm 1*, Otto W. Witte 2, Hubertus Axer2 und Julian Großkreutz2
1 University Hospital Basel, Neurology, Basel, Switzerland
2 Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany
Background: With the advent of high resolution muscle ultrasound the detection of neurogenic pathology has become feasible; its ability to reliably detect lower motor neuron disturbance in amyotrophic lateral sclerosis (ALS), however, is as yet not quite clear.
Objective: Our objective was to determine the utility of muscle ultrasound (MUS) in amyotrophic lateral sclerosis (ALS) in comparison to electromyography (EMG). Method: 60 patients with ALS and 20 patients with ALS-like disorders were studied using MUS and EMG. 30 healthy controls received MUS only (Figure 1). Echogenicity was graded semiquantitatively and occurrence of fasciculations and fibrillations in different anatomical regions was evaluated (Figure 2, 3 and 4). German Clinical Trials Register (DRKS-ID: DRKS )
Figure 3: Ultrasonic cross sections through the left and right tibialis anterior muscle (TA) showing different echogenicity: A) normal (starry night) (healthy control), B) Increased echo intensity with normal bone echo (patient with polyneuropathy), C) Increased echo intensity with reduced bone signal (ALSFRS 46), D) Increased echo intensity and loss of bone signal (ALSFRS 10).
Figure 5: Affection of LMN in 4 anatomical regions (bulbar, cervical, thorakal and lumbar) using combination of EMG and ultrasound
Figure 4: Ultrasonic cross sections through the left TA showing a fasciculation using M-mode
Figure 6: El Escorial criteria, Awaji-Shima criteria and MUS-criteria, abbreviations: AR = anatomical region, c = clinical, e = electrophysiological, LMN = lower motor neuron, UMN = upper motor neuron, u = ultrasonic
Figure 2. Heckmatt Score: Visual grading scale to classify muscle echo intensity in ultrasound (Heckmatt et al., 1982).
Figure 1 Study population: +/- Standard deviation. ALSFRS = ALS functional rating scale
Results: MUS detects fasciculations with a higher sensitivity than EMG (up to 30% higher). Also fibrillations were visible, but less often than in EMG. In bulbar muscles MUS indicates an overall higher sensitivity. Combining MUS and EMG significantly improves detection of lower motor neuron (LMN) degeneration and thus facilitates the diagnosis of ALS (Figure 5). Furthermore US revealed increased echo intensity (EI) in about 90% of ALS-patients with a significant increase of overall echotexture in all investigated muscles compared to patients with ALS-like disorders and to normal controls. Interestingly increased EI was also found in clinically and electrophysiologically unaffected muscles.
Conclusion:
1. Muscle ultrasound (MUS) detects fasciculations and fibrillations with high sensitivity in ALS and other neuromuscular disorders, especially in bulbar muscles.
2. Combination of EMG and MUS increases sensitivity in diagnosis of ALS and thus a new algorithm would be helpful.
3. MUS shows significant increased echo intensity in ALS compared to ALS-like disorders and healthy controls, also in clinically and electrophysiologically unaffected muscles.