Skin innervation across amyotrophic lateral sclerosis clinical stages: new prognostic biomarkers.

Over recent decades, peripheral sensory abnormalities, including the evidence of cutaneous denervation, have been reported among the non-motor manifestations in amyotrophic lateral sclerosis (ALS). However, a correlation between cutaneous innervation and clinical features has not been found. The aims of this study were to assess sensory involvement by applying a morpho-functional approach to a large population of ALS patients stratified according to King's stages and correlate these findings with the severity and prognosis of the disease. We recruited 149 ALS patients and 41 healthy controls. Patients undertook clinical questionnaires for small fibre neuropathy symptoms (Small Fiber Neuropathy Symptoms Inventory Questionnaire) and underwent nerve conductions studies (NCS) and 3-mm punch skin biopsies from leg, thigh and fingertip. We assessed intraepidermal nerve fibre (IENF) and Meissner corpuscle (MC) density by applying an indirect immunofluorescence technique. Moreover, a subset of 65 ALS patients underwent a longitudinal study with repeat biopsies from the thigh at 6- and 12-month follow-ups. Serum NfL levels were measured in 40 patients. Sensory symptoms and sensory NCS abnormalities were present in 32.2% and 24% of patients, respectively, and increased across clinical stages. Analogously, we observed a progressive reduction in amplitude of the sensory and motor ulnar nerve potential from stage 1 to stage 4. Skin biopsy showed a significant loss of IENFs and MCs in ALS compared with healthy controls (all P < 0.001). Across the clinical stages, we found a progressive reduction in MCs (P = 0.004) and an increase in IENFs (all P < 0.027). The increase in IENFs was confirmed by the longitudinal study. Interestingly, the MC density inversely correlated with NfL level (r = -0.424, P = 0.012), and survival analysis revealed that low MC density, higher NfL levels and increasing IENF density over time were associated with a poorer prognosis (all P < 0.024). To summarize, in patients with ALS, peripheral sensory involvement worsens in parallel with motor disability. Furthermore, the correlation between skin innervation and disease activity may suggest the use of skin innervation as a putative prognostic biomarker.

Cognitive impairment is associated with gait variability and fall risk in amyotrophic lateral sclerosis.

BACKGROUND: In amyotrophic lateral sclerosis (ALS), gait abnormalities contribute to poor mobility and represent a relevant risk for falls. To date, gait studies in ALS patients have focused on the motor dimension of the disease, underestimating the cognitive aspects. METHODS: Using a wearable gait analysis device, we compared gait patterns in ambulatory ALS patients with mild cognitive impairment (ALS MCI+; n = 18), and without MCI (ALS MCI-; n = 24), and healthy subjects (HS; n = 16) under two conditions: (1) normal gait (single task) and (2) walking while counting backward (dual task). Finally, we examined if the occurrence and number of falls in the 3 months following the baseline test were related to cognition. RESULTS: In the single task condition, ALS patients, regardless of cognition, displayed higher gait variability than HS, especially for stance and swing time (p < 0.001). The dual task condition revealed additional differences in gait variability parameters between ALS MCI+ and ALS MCI- for cadence (p = 0.005), stance time (p = 0.04), swing time (p = 0.04) and stability index (p = 0.02). Moreover, ALS MCI+ showed a higher occurrence (p = 0.001) and number of falls (p < 0.001) at the follow-up. Regression analyses demonstrated that MCI condition predicted the occurrence of future falls (ß = 3.649; p = 0.01) and, together with executive dysfunction, was associated with the number of falls (cognitive impairment: ß = 0.63; p < 0.001; executive dysfunction: ß = 0.39; p = 0.03), regardless of motor impairment at clinical examination. CONCLUSION: In ALS, MCI is associated with exaggerated gait variability and predicts the occurrence and number of short-term falls.

Correlation between Retinal Vascularization and Disease Aggressiveness in Amyotrophic Lateral Sclerosis.

Abnormalities in retinal vascularization and neural density have been found in many neurodegenerative diseases; however, conflicting results are described in Amyotrophic Lateral Sclerosis (ALS). The aim of the present study was, therefore, to systematically analyze retinal layers and vascularization by means of spectral-domain (SD-OCT) and optical coherence tomography angiography (OCT-A) in ALS patients. We enrolled 48 ALS patients and 45 healthy controls. ALS patients were divided into three groups: slow progressors (n = 10), intermediate progressors (n = 24) and fast progressors (n = 14), according to the disease progression rate. For SD-OCT, we evaluated the Subfoveal choroidal thickness (SFCT), ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL). Regarding the OCT-A, we assessed the vessel density (VD) in superficial and deep capillary plexuses, radial peripapillary capillary plexus, choriocapillary and the foveal avascular zone (FAZ) area. SD-OCT exam did not show any significant differences in GCC and RNFL thickness between patients and controls and among the three ALS groups. The SFCT was statistically greater in patients compared with controls (357.95 ± 55.15 µm vs. 301.3 ± 55.80 µm, p < 0.001); interestingly, the SFCT was thicker in patients with slow and intermediate disease progression than in those with fast disease progression (394.45 ± 53.73 µm vs. 393.09 ± 42.17 µm vs. 267.71 ± 56.24 µm, p < 0.001). OCT-A did not reveal any significant results. Amyotrophic Lateral Sclerosis Functional Rating Scale-Revised (ALSFRS-r) and disease duration did not correlate with any of the OCT parameters, except for SFCT with ALSFRS-r (r = 0.753, p = 0.024). This study demonstrated the possible association between choroidal thickness and disease activity in ALS. OCT could be a useful biomarker in the management of the disease.