idiopathic neuropathy treatmentidiopathic trigeminal neuropathyidiopathic autonomic neuropathyidiopathic progressive neuropathyidiopathic sensory neuropathyidiopathic optic neuropathyidiopathic small fiber neuropathyidiopathic axonal neuropathyidiopathic neuropathy in feetidiopathic polyneuropathyidiopathic neuropathy mayo clinicidiopathic peripheral