CHAPTER 6: The Brainstem, Cranial Nerves, and Visual Pathways

> CASE 6 Cavernous Malformation in the Pons

Sean thought it was odd when the tip of his right thumb went numb. He was playing soccer at San Jose State University, looking forward to getting one of the two coveted goalkeeper scholarships in the upcoming year. Over the next few weeks, he was increasingly tired and less athletic, and couldn’t focus or jump. The numbness spread down the entire right side of his body, becoming painful, like someone digging into him. He rapidly lost the ability to walk, and his right hand “shriveled up.” His family flew out to be with him, as he was initially diagnosed with a possibly fatal brainstem tumor. A subsequent MRI found a cavernous malformation in his pons. A cavernous malformation is a mass of abnormal blood vessels that appear as distended or dilated chambers. They tend to bleed slowly due to inadequate connective tissue support and poor quality smooth muscle and elastin that normally maintain vascular integrity. This low-flow lesion is differentiated from a high-flow cerebral arteriovenous malformation (AVM), which occurs when the normal capillary bed separating arteries and veins is absent, causing high-pressure distention of veins, which can burst, causing headaches, seizures, or stroke. Heavily sedated after the surgery, Sean barely recalls the four days in the hospital. However, the two weeks in the neurorehabilitation unit were miserable, with a bleak room, poor sleep quality, terrible food, and impossible therapy. Sean liked the therapists, but he couldn’t do anything they asked, and it was frustrating to constantly fail. In retrospect, he is incredibly grateful for the rehabilitation and credits his early recovery to services received, which allowed him to return home and continue his progress. The rehabilitation team worked on his recovery from damage to structures located within the pons and surrounding tissues. Speech therapy focused on compensatory strategies to manage his slurred speech (dysarthria), as he lost motor and sensory function on the left side of his face and around the mouth. Occupational therapy focused on food management due to loss of distal tongue sensation. To this day, Sean feels no difference between a fork and a finger, and must be careful with hot beverages that simply feel warm and cold beverages that register as painful. Fortunately, taste sensation was preserved. On the right side of his body, he had altered perception of pain and temperature, arm weakness, and spasticity. Postoperatively he reported poor balance and experienced a change of vision in his left eye, describing it as perceiving only color, but not image, when looking through that eye.