 Brian Stagg is one of our fourth year medical students from the University of Utah. And I've worked a lot with Brian, both in neurophemology clinic and outside of clinic. He is the, I don't know what your title is, but he's the student coordinator for the Fourth Street Clinic for all the volunteers there. He does a tremendous amount of work for that, and it's been my pleasure working with him, so welcome, Brian. Thanks for the introduction, Grant. As Grant said, I'm a fourth year medical student here at the University of Utah. In June I spent two weeks rotating in the neurophemology clinic, and this was a great experience for me because I felt like most of the patients we saw in the neurophemology clinic were kind of a diagnostic puzzle with multiple pieces fitting together to give the final diagnosis. And the patient I'm presenting today is an example of that. The patient was a 36-year-old right-handed male who was being evaluated for vision loss. He'd had a traumatic brain injury in March of this year, and associated with that he suffered multiple facial and orbital fractures. While in the hospital he was treated with bifuronal craniotomy, cranialization of the frontal sinuses, placement of a lumbar drain, and repair of the facial fractures. Also while in the hospital he had, the symptoms he had included, he had mild cognitive dysfunction, right-sided weakness, diabetes insipidus, and a six-nerve palsy. He also complained of visual disturbances. These visual disturbances were complicated and were very difficult for him to describe, both because of their complex nature and because of his cognitive impairment. But he described them as a field cut. When asked, when questioned further about this, he said that he was only able to see the right half of objects, but he also said that with the left eye he was only able to see to the right, and with the right eye he was only able to see to the left. Additionally he complained of double vision that he only noticed with near vision. After discharge from the hospital he spent some time in rehab, and then he also had meningitis in April of this year which was treated. His ocular history was non-contributory, and his neurological history prior to this event he had had no neurological problems. He was previously healthy. On physical exam his visual acuity was decreased in the right. His normal in the left, his pressures were normal, his pupils were equal, and he had no APD. His color vision with the Ishii Heart Test was within normal limits, but it showed an interesting finding. He would only comment on the right half of every number. So for example, what he called a three was actually an eight. He didn't have any stereo vision. He was unable to see the fly in 3B. And his phillistic confrontation were difficult to interpret because of problems with fixation. He had no proptosis. His right eye had minus four abduction, and he's isotropic in primary gaze in all directions. However, it was impossible to accurately measure his isotopia because of problems with fixation. It was difficult to tell where he was fixating and he would switch. At this point we decided to do visual field testing. His slit lamp exam was normal and he had some bilateral optic nerve pallor. His neurological exam was only significant for some cognitive slowing. So the field exam, his Humphrey visual field, showed a very clear bitemple hemianopsia, which was supported by the Goldman visual field. We ordered an MRI which showed disruption of the optic chiasm. It's difficult to capture in a single image to show the disruption of the optic chiasm. This was decided to be the best image that shows that disruption. Here's the second image supporting that. This image is also interesting because it shows disruption of the pituitary stalk, which goes along with the diabetes insipidus that the patient had been diagnosed with. At this point as a medical student I felt a little overwhelmed with the patient because he had multiple neurofumologic problems that were fitting together. I was also having a hard time understanding his visual field problems, his visual disturbance that he described as a field cut. I found it was useful for me to break it down into each individual diagnosis and then see how those fit together. So first diagnosis, we know he had a right six nerve palsy. We also knew that he had bitemple hemianopsia, as shown by the visual field testing. And the MRI showed that that was secondary to an optic chiasm injury. And then the third diagnosis from those is the hemifield slide that explains his visual disturbances. I'm going to talk a little bit more about each of these diagnoses. Diagnosis number one was the six nerve palsy. Six nerve palsy is the most frequent isolated oculomotor palsy and it results in impaired abduction and also esotropia. Differential diagnosis for causes of this in our patient include traumatic injury, could have been surgical injury, had some significant surgeries done in that area. He also had intracranial hypotension that was shown by a lumbar puncture and it could also have been caused by inflammation from a chronic or recovering meningitis that was also shown by a lumbar puncture. We expect gradual improvement with this six nerve palsy. Diagnosis number two is the bitemple hemianopsia. Here I have a diagram showing the normal visual fields in a patient with their representation on the retina, the optic nerve, chiasm and optic tract. In bitemple hemianopsia there's typically a lesion to the optic chiasm and what happens with this is the nasal retina of each eye is lost and that results in the loss of the visual field on the same side of that eye. For example, in the right eye with the optic chiasm lesion you lose the nasal retina on the right eye which would correspond to the right visual hemifield of the right eye. The right eye still maintains the left visual hemifield and with optic chiasm this happens in both eyes so the patient has both visual hemifields but only monocular representation in each visual hemifield. Also along with the bitemple hemianopsia our patient had a diabetes insipidus. I found a case series of 19 patients with traumatic chiasm injury and seven of those also had diabetes insipidus which makes sense with our understanding of the anatomy. You see the pituitary stalk and close proximity with the optic chiasm. So diagnosis number three is the hemifields slide or explaining the complex visual disturbance that the patient was describing. Here I have a diagram of a patient with an optic chiasm injury causing bitemple hemianopsia. But you'll recall our patient also had the sixth nerve palsy which results in esotropia of the right eye and with that esotropia as the right eye moves inward it shifts the left visual field laterally. So another diagram showing this, here's a normal visual field with the esotropia and the monocular representation in each visual hemifield that splits the two fields resulting in a blind area down the center of the patient's vision. Difficult to understand. Also you can see difficult for the patient to explain exactly what was going on as he switched fixation points. So definition of hemifields slide is horizontal or vertical deviation of images in the visual hemifields in patients with bitemple hemianopsia. This occurs because each visual hemifield is monocular and there are no areas of overlap between the visual half-fields. This makes it difficult for the brain to have linkage to maintain juxtaposition of the two visual half-fields and then you can split. So in our patient this was caused by the sixth nerve palsy. This can also happen just as a manifestation of euphoria when the brain loses the linkage to maintain that juxtaposition. So hemifields slide can cause three different things and I found it easiest for me to understand this using my hands, using my right hand to represent the vision coming from my right eye which is in the left visual hemifield and then the left hand represent the vision coming from the left eye which is in the right visual hemifield. You can see with exodeviation the two fields begin to overlap and the patient complains of double vision. With a hyperdeviation the images slide next to each other and then with an esodeviation which is what our patient had the two visual fields split and there's this strip of where the patient can't see down the middle. So in conclusion this is an uncommon phenomenon but I found it very interesting because it illustrates the functional anatomy and how they all play together. So to understand this patient I had to understand sixth nerve palsy resulting in esotropia and then with the monocular visual hemifields from the bitimple hemianoxia how that played together. This also made the importance of putting the entire picture together. Sometimes it's tempting to focus in on a single diagnosis but a lot of times those diagnoses play together to explain the patient's symptoms. Thank you for your time. I'll take any questions now. For one thing I think it's difficult for him to recover from the esotropia because he doesn't also pencil push ups and also I think as his esotropia improves he'll probably start to notice some double vision so it might be frustrating for him.