The anterolateral triangle is one of 10 surgical triangles of the cavernous sinus and serves as an important anatomic landmark for the skull base surgeon. There are few studies in the English literature that have precisely defined and measured the borders of the anterolateral triangle and little agreement has been made regarding the nomenclature within the English literature. A total of 12 midsagittally hemisected adult human cadaveric head halves were dissected to expose the anterolateral triangle. The triangle was defined and measurements of the anterior, posterior, and lateral borders were taken. The mean lengths and standard deviations of the anterior, posterior, and lateral borders were 8.3 ± 2.2 mm, 5.9 ± 2.0 mm, and 11.5 ± 2.9 mm, respectively. The mean area and standard deviation were 20.46 ± 9.30 mm2. The anterolateral triangle is helpful in understanding and planning surgical approaches to the cavernous sinus and middle cranial fossa. As such, normal anatomic relationships and the sizes of the anterolateral triangle must first be recognized to better access the pathologic changes within and around this region.

Background: Subacute combined degeneration (SCD) of the spinal cord with corticospinal tract involvement can impair motor functions below the level of the lesion. Case Report: A 63-year-old man developed progressive bilateral lower extremity weakness marked by difficulty standing for more than a second and the inability to ambulate, causing him to become wheelchair-bound. He was diagnosed with SCD. His vitamin B12 level was corrected and he underwent physical therapy. Despite these interventions, he experienced an overall deterioration in his strength examination. He later underwent an epidural spinal cord stimulator trial with pulsed electrical stimulation. With this, he experienced improvement in his lower extremity strength and regained the ability to ambulate independently. Permanent leads were placed with the retained faculty to ambulate with the stimulator turned on. Conclusion: Epidural spinal cord stimulation (SCS) has the potential to improve motor function and restore locomotion in individuals with spinal cord injury from SCD. Key words: Case report, epidural spinal cord stimulation, spinal cord injury, subacute combined degeneration

INTRODUCTION Primary CNS lymphoma (PCNSL) typically presents with non-focal neurologic symptoms including disorientation, poor balance and memory and singel or multifocal periventricular MRI lesions. Deviations in characteristic findings can delay diagnosis and require additional diagnostic tests. OBSERVATION A 68-year-old man with a recent zoster infection and acetylcholine receptor antibody positive myasthenia gravis (MG) on Mycophenolate Mofetil for 22 years presented at another institution with left eye vision changes, and focal neurological deficits. A brain MRI showed an enhancing lesion within his left medulla extending to the cerebellum. Cerebrospinal fluid (CSF) analysis was positive for EBV and negative for malignancy. He was diagnosed with VZV vasculopathy and discharged home on IV Acyclovir for 14 days and a 5-day course of oral prednisone 60 mg. Three months later, a repeat brain MRI showed multiple new enhancing lesions bilaterally along the periventricular white matter with involvement of the corpus callosum with several lesions in peripheral locations of the cerebrum, cerebellum, and brainstem. He presented to local ER with intermittent encephalopathy, acute left eye vision blurriness and was started on steroids. He was transferred to our institution and had CSF analysis which was positive for EBV and negative for malignancy. Due to rapid progression of his symptoms, he underwent gross total resection of the left frontal lesion which showed EBV-induced diffuse large B-cell lymphoma (DLBCL). His Mycophenolate Mofetil was discontinued and he had a dramatic improvement in his left eye vision and cognitive deficits within 24 hours after one dose of Rituximab IV 500 mg/m2. DISCUSSION In the setting of periventricular lesions and EBV positivity on CSF, EBV-induced DLBCL should be highly considered. CONCLUSION Misdiagnosis or delay in diagnosis of PCNSL due to the presence of atypical features in disease presentation and radiographic findings could lead to progression of PCNSL.

Patients with primary central nervous system lymphoma (PCNSL) typically present with non-focal neurological symptoms, including disorientation, poor balance and memory loss with unifocal or multifocal periventricular lesions seen on MRI. Deviations from these characteristic findings can delay diagnosis and lead to additional diagnostic tests being needed. The present study reports a 68-year-old man with a recent varicella zoster infection and history of acetylcholine receptor antibody-positive myasthenia gravis who received mycophenolate mofetil for 22 years. He presented with left eye vision changes and cognitive memory deficits. A brain MRI showed an enhancing lesion within his left medulla extending to the cerebellum. Cerebrospinal fluid analysis was positive for Epstein-Barr virus (EBV) and negative for malignancy. He was diagnosed with varicella zoster virus vasculopathy. At 3 months later, a repeat brain MRI showed multiple new enhancing lesions developing bilaterally along the periventricular white matter. Soon after, he presented to a local ER with acute left-sided blurry vision and worsening memory loss, and he began receiving steroids. Because of rapid symptom progression, he underwent resection of the left frontal lesion, which showed EBV-induced diffuse large B-cell lymphoma (DLBCL). Mycophenolate mofetil was discontinued, and within 24 h of one dose of intravenous 500 mg/m 2 rituximab, he had a dramatic improvement in left eye vision and memory loss. He experienced mixed responses to rituximab after 3 cycles. Following one dose of high-dose methotrexate, he developed subsequent chronic kidney disease and required dialysis. He received whole-brain radiation therapy with craniospinal radiation and is currently in complete remission. An EBV-induced DLBCL diagnosis should be highly considered for patients with periventricular lesions and EBV-positive cerebrospinal fluid. Misdiagnosis or delay in PCNSL diagnosis because of atypical features in disease presentation and radiographic findings could lead to PCNSL progression and worsening neurological deficits.