Abstract
BackgroundAmyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with progressive motor system impairment, and recent evidence has identified the extra-motor involvement. Small fiber neuropathy reflecting by sensory and autonomic disturbances in ALS has been reported to accompany the motor damage. However, non-invasive assessment of this impairment and its application in disease evaluation of ALS is scarce. We aim to evaluate the use of corneal confocal microscopy (CCM) to non-invasively quantify the corneal small fiber neuropathy in ALS and explore its clinical value in assessing disease severity of ALS.MethodsSixty-six patients with ALS and 64 healthy controls were included in this cross-sectional study. Participants underwent detailed clinical assessments and corneal imaging with in vivo CCM. Using ImageJ, the following parameters were quantified: corneal nerve length (IWL) and dendritic cell density (IWDC) in the inferior whorl region and corneal nerve fiber length (CNFL), nerve fiber density (CNFD), nerve branch density (CNBD), and dendritic cell density (CDC) in the peripheral region. Disease severity was evaluated using recognized scales.ResultsCorneal nerve lengths (IWL and CNFL) were lower while dendritic cell densities (IWDC and CDC) were higher in patients with ALS than controls in peripheral and inferior whorl regions (p < 0.05). Additionally, corneal nerve complexity in the peripheral region was greater in patients than controls with higher CNBD (p = 0.040) and lower CNFD (p = 0.011). IWL was significantly associated with disease severity (p < 0.001) and progression (p = 0.002) in patients with ALS. Patients with bulbar involvement showed significantly lower IWL (p = 0.014) and higher IWDC (p = 0.043) than patients without bulbar involvement.ConclusionsCCM quantified significant corneal neuropathy in ALS, and alterations in the inferior whorl region were closely associated with disease severity. CCM could serve as a noninvasive, objective imaging tool to detect corneal small fiber neuropathy for clinical evaluation in ALS.
Highlights
Amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease, is characterized by progressive paralysis, dysphagia, respiratory failure, and eventual death [1]
The validation of facial-onset sensory and motor neuronopathy (FOSMN) as a rare phenotype of ALS provides supporting evidence for this small fiber neuropathy, as it starts from trigeminal sensory disturbance to bulbar and limb weaknesses [8, 9]
The ALS group consisted of 41 males and 25 females, and the control group consisted of 38 males and 26 females
Summary
Amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease, is characterized by progressive paralysis, dysphagia, respiratory failure, and eventual death [1]. ALS as a multisystem disease with nonmotor involvement, including metabolic imbalance, sleep disorder, and peripheral neuropathies with minor sensory and autonomic disturbances [3,4,5]. The damage is to a much lesser extent than motor impairment, studies have reported clinical and electrophysiological results of sensory and autonomic damage in approximately 10–30% of ALS patients [6, 7]. The validation of facial-onset sensory and motor neuronopathy (FOSMN) as a rare phenotype of ALS provides supporting evidence for this small fiber neuropathy, as it starts from trigeminal sensory disturbance to bulbar and limb weaknesses [8, 9]. Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder with progressive motor system impairment, and recent evidence has identified the extra-motor involvement. Small fiber neuropathy reflecting by sensory and autonomic disturbances in ALS has been reported to accompany the motor damage. We aim to evaluate the use of corneal confocal microscopy (CCM) to non-invasively quantify the corneal small fiber neuropathy in ALS and explore its clinical value in assessing disease severity of ALS
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