There are many symptoms of Surfer's Myelopathy. Here are some resources that list them:
Surfer’s myelopathy: A review of etiology, pathogenesis, evaluation, and management
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Surfer's Myelopathy happens from hyperextension of the back, so it can happen with any activity that hyperextends the back. Here are some resources that list the causes:
Surfer’s myelopathy: A review of etiology, pathogenesis, evaluation, and management
Surfer’s Myelopathy : Case Series and Literature Review