question: Hello doctor,If a person had been diving and experienced an arterial gas embolism in the spinal cord. Specifically, it was disrupting the nerve root for the T8 or S1 dermatome. Would the whole region of the dermatome be affected with decreased sensation? Meaning, would it wrap around the torso (T8) or down the calf (S1) or is it possible to have an isolated numb spot within the T8 or S1 dermatome itself? What specifically would you do to test and map out the area of the deficiency and how would the symptoms truly present? If you were testing the cranial nerves for deficiencies, would it matter if the patient can see you touching his skin for the trigeminal nerve?