Cross-Sectional Area Reference Values of Nerves in the Upper and Lower Extremities using Ultrasonography in the Indian Population.

Background and Purpose: Cross-sectional area (CSA) is the most important parameter to study peripheral nerves by high-resolution ultrasonography. The aim was to acquire normative data of CSA of the main upper and lower limb nerves in the Indian population. Methods: CSA of nerves was determined in 100 healthy volunteers at 11 predetermined sites: median and ulnar at the wrist, mid-forearm, elbow; radial (spiral groove); tibial (popliteal fossa, medial malleolus); common peroneal (CPN, fibular head) and sural (lateral malleolus). Results: The mean age of participants was 40.7 ± 13.0 years (range: 18-79). Fifty were < 40 years of age. The mean height, weight and BMI were 161.5 ± 8.3 centimeters (range: 145-179), 58.6 ± 10.1 kilograms (range: 32-90) and 22.4 ± 3.2 kilogram/square meter (range: 14.03-30.44), respectively. The median and ulnar nerve measurements were non-uniform throughout its course, and the CSA was largest at the elbow and ulnar groove, respectively. With advancing age, there was a significant difference for median and ulnar nerves at the wrist (median P = 0.002, ulnar P = 0.009) and tibial nerve (popliteal fossa, P = 0.045, medial malleolus, P = 0.005), CPN (P = 0.047). Men had greater CSA of upper limb nerves and tibial nerves at popliteal fossa (P < 0.05) as compared to women. A positive correlation was noted with weight. Conclusion: It is apt for every defined population to have its own set of normative data of CSA as it varies with ethnicity, age, and the built of individuals. We provide a valuable set of CSA data for nerves in the Indian population, which can be used for comparison while investigating peripheral nerve disorders.

Diaphragmatic ultrasound: Prospects as a tool to assess respiratory muscle involvement in amyotrophic lateral sclerosis.

BACKGROUND: Ultrasonography (USG) of the diaphragm is a promising alternative to pulmonary function tests (PFT) for assessing respiratory function in amyotrophic lateral sclerosis/motor neuron disease (ALS/MND). METHODS: We studied 33 patients fulfilling Awaji criteria (definite = 14; probable = 12; possible = 7) and 33 age and gender-matched controls. Diaphragm thickness was measured using USG at the end of expiration (DTex) and end of inspiration (DTin). The thickness ratio (TR) was calculated as DTin/DTex. The mean age at onset and duration were 49.73 ± 12.7 years and 13.57 ± 9.7 months, respectively. Men = 25 (75.8%); Limb onset ALS/MND = 24 patients (72.7%); bulbar onset = 9 (27.3%). RESULTS: Compared to controls, ALS/MND patients had reduced mean DTex (2.22 ± 0.29 mm vs. 2.02 ± 0.32 mm, p = .012) and DTin (4.0 ± 0.71 mm vs. 3.41 ± 0.38 mm, p < .001). PFTs done in 31 patients showed restrictive abnormality in 80.6%. Significant positive correlation was seen between percentage of predicted forced vital capacity (FVC%) and DTin (p = .009) and TR (p = .037) but not with DTex (p = .852). No significant correlation was seen between diaphragmatic thickness and other PFT parameters or ALSFRS scores. CONCLUSION: The diaphragmatic thickness showed a significant decrease in ALS/MND as compared to controls. End-inspiratory diaphragmatic thickness and TR correlated well with %FVC. Thus, diaphragmatic USG could be a potential alternative to PFTs in assessing respiratory function in ALS/MND patients having the advantage of less patient participation and ease of performing in late stages of ALS/MND.

Muscle ultrasonography in detecting fasciculations: A noninvasive diagnostic tool for amyotrophic lateral sclerosis.

BACKGROUND AND OBJECTIVES: Muscle ultrasound (MUS) is an emerging noninvasive tool to identify fasciculations in amyotrophic lateral sclerosis (ALS). We assessed the utility of MUS in detecting fasciculations in suspected ALS patients. METHODS: Thirty-three patients (25 men) with possible (n = 7), probable (n = 12), or definite ALS according to Awaji criteria were studied. Electromyography was done in biceps brachii, quadriceps, and thoracic paraspinal muscles and MUS in biceps, triceps, deltoid, abductor-digiti-minimi, quadriceps, hamstrings, tibialis anterior, thoracic paraspinal, and tongue muscles. RESULTS: The age at onset and illness duration was 49.73 ± 12.7 years and 13.57 ± 9.7 months, respectively. Limb-onset = 24 patients (72.7%) and bulbar-onset = 9 (27.3%). Totally 561 muscles were examined by MUS. Fasciculations were detected in 84.3% of muscles, 98.4% with and 73% without clinical fasciculations (p < 0.001). Fasciculation detection rate (FDR) by MUS was significantly higher in muscles with wasting (95.6%) than without wasting (77.6%, p < 0.001). Compared with EMG, FDR was significantly higher with MUS in quadriceps (81.8% vs. 51.5%, p = 0.002) and thoracic paraspinal muscles (75.8% vs. 42.4%, p = 0.013). The proportion of patients with definite ALS increased from 42% by clinical examination to 70% after combining EMG and MUS findings. CONCLUSIONS: MUS is more sensitive in detecting fasciculations than electromyography (EMG) and provides a safer, faster, painless, and noninvasive alternative to EMG in detecting fasciculations in ALS.