{'fraction_non_alphanumeric': 0.026829268292682926, 'fraction_numerical': 0.00878048780487805, 'mean_word_length': 5.573717948717949, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Quantification of Trigeminovascular Hypersensitivity in a Chronic Migraine Patient Using Laser Speckle Contrast Analysis (LASCA).

BACKGROUND
Activation of peripheral and/ or central trigeminovascular pain pathways are implicated in the pathogenesis of migraine. Small fibers mediate pain, thermal sensation and autonomic functions. Axon-flare response is correlated with local C-fiber activation and CGRP release. LASCA detects very subtle microcirculatory changes which is not visible by naked eye.


CASE
Axon-flare response was elicited by intradermal (i.d.) 0.01 ml histamine introduced to the left forehead, trigeminal nerve ophtalmic branch (V1) skin area. Skin microvascular blood flow data was recorded using a LASCA, real-time microcirculation imaging system. In the healthy control, prick stimulus slightly elevated focal skin microcirculation only at the stimulated focal area. However, in our chronic migraine patient, the unilateral prick stimulation transiently (10-12 seconds) increased ipsilateral skin microcirculation at all 3 branches of the trigeminal nerve with a slight expansion across the midline. Besides, left V1 stimulation by histamine i.d. induced not only prominent but also long lasting (10-15 minutes of recording time) axon flare response at ipsilateral V1, V2, V3, and even with an expansion to the contralateral V1 without any report of allodynia or hyperalgesia. The treatment decreased axon-flare characteristics probably by inhibiting the neurogenic inflammation.


DISCUSSION
The clinical characteristics and individual response to treatment varies widely across pain patients. Here, we demonstrated the presence of transient spread of increased microcirculation at ipsilateral trigeminal, and also across the midline after prick stimulus, whereas a more prominent, widespread, and long-lasting, histamine-induced axon flare response in a rare subclass of chronic migraine patient with autonomic symptoms. The modulatory effect of the pharmacological intervention has also been objectively quantified by LASCA.