{'fraction_non_alphanumeric': 0.026223776223776224, 'fraction_numerical': 0.005244755244755245, 'mean_word_length': 5.662790697674419, '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}}
Spontaneous regression of arteriovenous malformations.

Spontaneous regression of an arteriovenous malformation (AVM) is quite rare. When a regression does occur, there is usually an associated factor, such as intracranial hemorrhage, operation, radiation therapy, or new neurological deficit. Twenty-one cases of AVM regression identified in the literature are reviewed. An additional case in which the resolution was totally spontaneous is presented. Regressions occurred over intervals ranging from 7 months to 21 years. Several mechanisms for regression are discussed.