The diagnostic value of midbrain hyperechogenicity in ALS is limited for discriminating key ALS differential diagnoses.

BACKGROUND: Hyperechogenicity of the substantia nigra was recently reported in patients with sporadic ALS with a frequency similar to PD. Data on the diagnostic utility compared to key differential diagnoses of ALS do not exist yet. METHODS: We prospectively enrolled 43 patients with ALS, 29 with myasthenia gravis, 25 patients with inflammatory neuropathy, and 13 with cervical canal stenosis. All patients were examined by a blinded investigator using transcranial B-mode sonography planimetrically measuring hyperechogenic areas of the midbrain representing the substantia nigra. RESULTS: Mean midbrain hyperechogenic area was increased in ALS compared to non-ALS differentials. ROC analysis revealed only small area under the curve for detecting ALS (AUC: 0.669 [95%CI: 0.56-0.78]; p = 0.006). Highest Youden index was observed for area size of <0.14 cm(2) (Youden index: 0.28). Using this cut-off score and that generated from normative data of healthy controls, area size measurements provided a sensitivity of only 46-58% and specificity of 69-83% for detecting ALS. No correlations of hyperechogenic area sizes in ALS patients were found to age, gender, ALS subtype (bulbar versus spinal form), disease duration or ALS-FRS-R score. CONCLUSIONS: Midbrain hyperechogenicity is reproducibly found in ALS patients, but its diagnostic value for discriminating ALS from its key differentials is limited.

Parkinson's disease-like midbrain hyperechogenicity is frequent in amyotrophic lateral sclerosis.

Clinical and neuroimaging data suggest impairment of the nigrostriatal system in amyotrophic lateral sclerosis (ALS). We thus hypothesized whether Parkinson's disease (PD)-like midbrain sonography findings are also present in ALS. Eighty-six patients with the diagnosis of possible or definite ALS according to revised El Escorial criteria were examined by transcranial B-mode sonography compared to 76 age- and gender-matched controls and 33 PD patients. Hyperechogenic areas of the midbrain representing the substantia nigra were measured planimetrically using standard protocols. In subjects with sufficient temporal acoustic bone windows, mean midbrain hyperechogenic areas were significantly higher in ALS (0.251 ± 0.104 cm(2)) and PD patients (0.286 ± 0.078 cm(2)) compared to controls (0.091 ± 0.054 cm(2)) with no significant difference between ALS and PD patients (one-way ANOVA: F value = 94.3; P < 0.0001). Sixty-seven percent (95 % CI 57-78 %) of ALS patients and 84 % (95 % CI 71-97 %) of PD patients displayed abnormal midbrain hyperechogenic areas (P = 0.383 for group comparison, χ(2) test). No correlations of hyperechogenic area sizes in ALS patients were found in regard to age, gender, ALS subtype (bulbar versus spinal form) or ALS-FRS-R score. In summary, we observed hyperechogenicity of the substantia nigra in patients with sporadic ALS with a frequency similar to that in PD and higher than in all other movement disorders. These findings are important for the diagnosis and differential diagnosis of PD and ALS alike.