Zoë R. Williams

Diffusion Tensor Imaging of the Optic Nerve in Multiple Sclerosis: Association with Retinal Damage and Visual Disability

BACKGROUND AND PURPOSE: There is a well-known relationship between MS and damage to the optic nerve, but advanced, quantitative MR imaging methods have not been applied to large cohorts. Our objective was to determine whether a short imaging protocol (<10 minutes), implemented with standard hardware, could detect abnormal water diffusion in the optic nerves of patients with MS. MATERIALS AND METHODS: We examined water diffusion in human optic nerves via DTI in the largest MS cohort reported to date (104 individuals, including 38 optic nerves previously affected by optic neuritis). We also assessed whether such abnormalities are associated with loss of visual acuity (both high and low contrast) and damage to the retinal nerve fiber layer (assessed via optical coherence tomography). RESULTS: The most abnormal diffusion was found in the optic nerves of patients with SPMS, especially in optic nerves previously affected by optic neuritis (19% drop in FA). DTI abnormalities correlated with both retinal nerve fiber layer thinning (correlation coefficient, 0.41) and loss of visual acuity, particularly at high contrast and in nerves previously affected by optic neuritis (correlation coefficient, 0.54). However, diffusion abnormalities were overall less pronounced than retinal nerve fiber layer thinning. CONCLUSIONS: DTI is sensitive to optic nerve damage in patients with MS, but a short imaging sequence added to standard clinical protocols may not be the most reliable indicator of optic nerve damage.

White matter changes linked to visual recovery after nerve decompression

Rapid remyelination is a major contributor to the normalization of vision after surgical removal of pituitary tumors in human patients and decompression of the optic chiasm. The Healing Brain In a new study, Paul et al. use magnetic resonance imaging in human patients to predict recovery of vision after surgery to remove pituitary gland tumors that have compressed the optic nerve. They found that after tumor removal, the insulation of the nerves regenerated rapidly and that this could be used as a direct marker of vision recovery. This suggests that the brain has a unique ability to heal. A deeper understanding of this healing process could advance treatments for a number of pathologies of the central nervous system involving nerve injury. The relationship between the integrity of white matter tracts and cortical function in the human brain remains poorly understood. We investigate reversible white matter injury, in this case patients with compression of the optic chiasm by pituitary gland tumors, to study the structural and functional changes that attend spontaneous recovery of cortical function and visual abilities after surgical removal of the tumor and subsequent decompression of the nerves. We show that compression of the optic chiasm led to demyelination of the optic tracts, which reversed as quickly as 4 weeks after nerve decompression. Furthermore, variability across patients in the severity of demyelination in the optic tracts predicted visual ability and functional activity in early cortical visual areas. Preoperative measurements of myelination in the optic tracts predicted the magnitude of visual recovery after surgery. These data indicate that rapid regeneration of myelin in the human brain is a component of the normalization of cortical activity, and ultimately the recovery of sensory and cognitive function, after nerve decompression. More generally, our findings demonstrate the use of diffusion tensor imaging as an in vivo measure of myelination in the human brain.

Arteriovenous malformations and carotid-cavernous fistulae.

Arteriovenous malformations of the brain or orbit often remain silent and asymptomatic unless growth or hemorrhage occurs. Treatment is directed at minimizing the risk of further hemorrhage and may be surgical or radiologic. Carotid-cavernous (or other arteriovenous) fistulae, in contrast, result from rupture of 1 or more arterial branches into the cavernous sinus, leading to orbital or intracranial symptoms from the flow of arterial blood through previously low-flow venous channels. Endovascular closure of the fistulous connection is the mainstay of treatment and may be accomplished through a number of transvenous or transarterial routes. Vascular malformations of both the orbit and the brain are likely to present with neuro-ophthalmologic symptoms. Common symptoms include eye pain and/or redness, diplopia from ocular dysmotility, ptosis, periorbital fullness or swelling, proptosis, and loss of central or peripheral vision. Patients also may experience headache, tinnitus, imbalance, dizziness, or neck pain. In this review, we describe the classification, clinical presentation, and treatment of arteriovenous malformations and carotid-cavernous fistulae, which are the most common vascular disorders that result primarily in ocular, orbital, or other neuro-ophthalmologic symptoms regardless of anatomic location.

Central Retinal Artery Occlusion With Subsequent Central Retinal Vein Occlusion in Biopsy-Proven Giant Cell Arteritis.

Central retinal artery occlusion with subsequent central retinal vein occlusion in the same eye is a rare entity. We present a 72-year-old man with biopsy-proven giant cell arteritis who developed bilateral arteritic anterior ischemic optic neuropathy and a left central retinal artery occlusion. Subsequently, he developed a left central retinal vein occlusion within 2 weeks of his initial vision loss. His vision did not improve with corticosteroids.

The immunopathology of giant cell arteritis: diagnostic and therapeutic implications.

W e read with great interest the article “The immunopathology of giant cell arteritis: diagnostic and therapeutic implications” by Weyand et al (1) and commend the authors on their comprehensive review of giant cell arteritis (GCA) immunopathogenesis and excellent discussion of potential new therapeutic targets. Due to the adverse effects of steroids and lack of therapeutic response in some patients with GCA, clinicians have investigated the use of steroid-sparing agents, including anti-tumor necrosis factor (anti-TNF)-a agents, for GCA treatment. Case reports on the use of anti-TNF-a antibodies for GCA and one small placebo-controlled trial investigating the use of etanercept in GCA patients have been promising (2–7). However, occurrences of GCA despite use of anti-TNF-a antibodies have been reported in the literature (8,9). We add to these reports with a patient who developed arteritic anterior ischemic optic neuropathy secondary to biopsy-proven GCA despite use of etanercept, an anti-TNF agent. A 59-year-old Caucasian woman with rheumatoid arthritis treated with etanercept and leflunomide was referred for evaluation of sudden peripheral vision loss in her right eye. She reported a 2-week history of intermittent bilateral blurred vision and transient binocular vertical diplopia. She noted transient obscurations of vision during the week before her loss of vision. She also reported a 1-month history of bilateral jaw claudication, low-grade fevers and malaise, a 3-week history of daily global headaches, and weight loss of 15 lbs over the previous 6 weeks. She had been taking leflunomide for 2.5 years and etanercept for 1.5 years. Etanercept was discontinued for 3 weeks due to her low-grade fever and malaise and was restarted 1 week before her vision loss. On examination, her best-corrected visual acuity was 20/25 in each eye. Her color vision was slightly decreased in the right eye and full in the left eye (13/14 and 14/14 Hardy-HandRittler plates, respectively). A right afferent pupillary defect was present. Automated visual field 24-2 SITA Standard testing demonstrated dense superior altitudinal and inferior arcuate defects in her right eye. Her left visual field was normal. Fundus examination revealed pallid optic disc edema with associated peripapillary hemorrhage in the right eye and a normal appearing disc in the left eye (Fig. 1). The right superficial temporal artery pulse was not palpable. Laboratory workup was notable for an erythrocyte sedimentation rate of 106 mm/hr and a C-reactive protein of 55.1 mg/L (normal: 0–10 mg/L). The patient was immediately treated with 100 mg of prednisone and a right temporal artery biopsy performed the same day demonstrated active GCA. She was subsequently admitted and treated with methylprednisolone (250 mg intravenously 4 times a day) for 3 days and aspirin (81 mg) daily. At 1-month follow-up, her best-corrected

Spontaneous in-flight accommodation of hand orientation to unseen grasp targets: A case of action blindsight

ABSTRACT The division of labour between the dorsal and ventral visual pathways is well established. The ventral stream supports object identification, while the dorsal stream supports online processing of visual information in the service of visually guided actions. Here, we report a case of an individual with a right inferior quadrantanopia who exhibited accurate spontaneous rotation of his wrist when grasping a target object in his blind visual field. His accurate wrist orientation was observed despite the fact that he exhibited no sensitivity to the orientation of the handle in a perceptual matching task. These findings indicate that non-geniculostriate visual pathways process basic volumetric information relevant to grasping, and reinforce the observation that phenomenal awareness is not necessary for an object’s volumetric properties to influence visuomotor performance.