<p>Corneal subbasal nerve plexus changes in patients with episodic migraine: an in vivo confocal microscopy study</p>

Abstract

Background and purpose: It has been generally thought that activation and sensitization of the trigeminovascular system may contribute to the pathogenesis of migraine. Nevertheless, there is little evidence on abnormalities in peripheral trigeminal afferent nerves from humans in vivo. Alterations of corneal nerves from the ophthalmic branch of the trigeminal nerve may support the notion that trigeminal afferent nerves are involved in migraine pathophysiology. The aim of the present study was to investigate the structural changes in corneal subbasal nerve plexus in patients with episodic migraine (EM) with in vivo confocal microscope (IVCM). Methods: In this cross-sectional observational study, 10 EM patients and 10 age- and sex-matched healthy controls were included. Analysis of IVCM images with Image J software was performed to quantify the changes in the corneal subbasal nerve plexus. Results: EM patients showed an increase in nerve fiber length (25.0±2.65 vs 22.3±2.41 mm/mm 2 , p =0.047) and nerve fiber density (36.3±7.29 vs 30.5±6.19 fibers/mm 2 , p =0.104) as compared with normal controls, but this difference was not statistically significant. Nerve branching and tortuosity were significantly increased in the EM subjects compared to the normal subjects (91.3±13.8 vs 75.0±14.2 branches/mm 2 , p =0.030 and 2.30±0.46 versus 1.63±0.52, p =0.011, respectively). In addition, nerve sprouts and increased number of Langerhans cells were observed in the EM patients. Conclusion: The morphologic changes of corneal subbasal nerve plexus and Langerhans cell aggregation suggest the presence of nerve regeneration and inflammation in EM. Furthermore, the alterations of corneal nerves from the ophthalmic branch of the trigeminal nerve offer support for the hypothesis that the peripheral trigeminal system may be involved in the pathogenesis of migraine.

Corneal Confocal Microscopy Demonstrates Corneal Nerve Loss in Patients With Trigeminal Neuralgia

“…CNFD and CNFL are reduced in patients with chronic migraine ( 19 ), especially those with photophobic migraine ( 20 ). However, in a recent study of patients with episodic migraine, nerve branching and tortuosity and Langerhans cell density were increased compared to controls, which are indicative of nerve regeneration and inflammation ( 21 ). In a recent study of patients with burning mouth syndrome, corneal nerve fiber density and length were lower and Langerhans cell density was higher compared to control subjects ( 22 ).…”

“…Corneal nerve fiber density (CNFD) and corneal nerve fiber length (CNFL) are reduced in patients with chronic migraine ( 19 ), especially those with photophobia ( 20 ), although a recent study has demonstrated increased corneal nerve branch density and tortuosity and Langerhans cells in patients with episodic migraine ( 21 ). We have recently shown a reduction in corneal nerve fiber density and length and an increase in Langerhans cell density in patients with burning mouth syndrome ( 22 ).…”

Exploring the Link Between Dry Eye and Migraine: From Eye to Brain

“…Corneal nerve branching and tortuosity were significantly increased in individuals with migraine compared to controls (91 ± 13.8 vs 75 ± 14.2 branches/mm 2 , p=0.03 and 2.3 ± 4.6 vs 1.6 ± 0.5, p=0.01, respectively). 73 Photophobia has also been linked to peripheral corneal nerve abnormalities. In a prospective Indian study, individuals with chronic migraine and photophobia (n=36) had significantly lower subbasal nerve parameters, including corneal nerve fiber length (14.8 ± 4.0 vs 18.1 ± 3.3 mm/mm 2 , p=0.007), compared to those with migraine but no photophobia (n=24).…”

Trigeminal Nerve Affection in Patients with Neuro-Sjögren Detected by Corneal Confocal Microscopy

“…Among the components of this avascular tissue, the nerves are of particular interest, as changes in their morphology and/or quantification serve as pointers towards understanding the presentation and progression of a wide range of not only keratopathies, but also neurovascular and neurodegenerative diseases. The characteristics of corneal nerves in systemic conditions associated with peripheral neuropathies such as diabetes, Fabry’s disease, Behçet’s and Parkinson’s disease have been studied [ 11 , 12 , 13 , 14 , 15 , 16 ].…”