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Senior patient complains of double vision
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A 66-year-old man presented to the Veterans Administration eye clinic reporting a sudden onset of double vision beginning 5 days earlier. The condition had remained constant since onset and disappeared when he closed either eye. He noted horizontal double vision regardless of direction of gaze.
The patient reported no other visual symptoms or eye pain and he denied any headaches or recent head or ocular trauma. He also denied any symptoms of slurred speech, facial asymmetry or numbness and tingling in his extremities.
His medical history included hypertension, chronic obstructive pulmonary disease, gait difficulties due to longstanding knee osteoarthritis and chronic alcoholism. His medication regimen included meloxicam, alendronate, albuterol and low-dose aspirin.
Upon examination, the patient’s best-corrected visual acuity was 20/25 in each eye. Confrontational fields were full to careful finger counting in each eye. His pupils were round and reactive to light with no relative afferent pupillary defect. Extraocular motility revealed adduction and abduction deficits in each eye with nystagmus in all gazes except primary. Cover test revealed 16 prism diopters of esotropia in all horizontal gaze positions, although it was difficult to measure in extreme gazes due to nystagmus.
Examination of the anterior segment was unremarkable except for mild age-appropriate cataracts in both eyes. Intraocular pressures were normal, measuring 17 mm Hg OD and 14 mm Hg OS. Dilated fundus examination was unremarkable with distinct margins, and the cup-to-disc ratio in each eye was 0.40H/VH/V, with no disc edema or disc pallor noted.
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Our initial differential diagnosis included localized microvascular event, cerebral vascular accident (CVA) and Wernicke’s encephalopathy due to a history of alcoholism. After a confirmatory consult with our staff neuro-ophthalmologist, we diagnosed the patient with bilateral gaze palsy and gaze-evoked nystagmus. He was sent to our emergency department for a stroke work-up to rule out any acute process.
The emergency department consulted with neurology and they added myasthenia gravis to the differential diagnosis. A brain CT scan and magnetic resonance imaging (MRI) were performed and revealed no acute intracranial findings such as hemorrhage, infarct, mass or midline shift. However, on MRI, prominent cerebellar and global atrophy and questionable subtle posterior pontine/aqueductal FLAIR hyperintensity were noted.
This patient’s management
Neurology diagnosed the patient empirically with Wernicke’s encephalopathy and admitted him to begin empirical thiamine treatment. The patient received 500 mg of intravenous thiamine three times a day for 2 days followed by 250 mg once a day for 5 days. The patient’s diplopia resolved 3 days after beginning treatment, and he was discharged from the hospital with orders to continue 100 mg of oral thiamine daily. He declined alcohol abuse counseling. While he continues to have mild residual gaze-evoked nystagmus, he has had no recurring diplopic episodes.
Classic signs, symptoms
Wernicke’s encephalopathy (WE) is an acute neurological disorder resulting from severe thiamine (vitamin B1) deficiency. Causes include long-term alcoholism, chemotherapy, prolonged starvation and bariatric surgery.
The classic triad of symptoms and signs of WE include mental confusion, difficulty with involuntary eye movements and difficulty coordinating movements, especially of the lower limbs. Unfortunately, 16% to 38% of patients demonstrate the classic signs of the condition, and 80% of patients with confirmed Wernicke’s encephalopathy were diagnosed post-mortem (Nishimoto et al.). Long-term thiamine deficiency can lead to Korsakoff’s psychosis and ultimately death.
Making the diagnosis
Image: Sellechio J
The diagnosis of WE can be made empirically or through MRI. MRI typically shows symmetric intensity of the thalamus, mamillary bodies, tectal plates and periaqueductal area; however, there can be alterations to other areas such as the cerebellum and cerebrum. With the exception of bilateral gaze palsy and end-gazed nystagmus, our patient exhibited no other signs of WE, and no definitive MRI findings were present.
In general, acquired nystagmus and/or extraocular muscle restriction disorders require prompt evaluation. Nystagmus is defined as repetitive, involuntary, rhythmic eye movements and can be classified as physiologically induced, congenital or infantile, and acquired. Our patient presented with acquired nystagmus, which is caused by a neurological disorder that disrupts the maintenance of foveal fixation. Acquired nystagmus can be classified as jerk or pendular. Jerk nystagmus occurs when the eyes drift toward one direction (slow phase), then rapidly return to the original position (fast phase). Pendular nystagmus occurs when there are two phases of equal frequency and amplitude, giving the appearance of sinusoidal back-and-forth eye movements.
Gaze-evoked nystagmus is one of the most frequently encountered types of nystagmus in clinical practice. It occurs only when the eyes try to maintain fixation in eccentric gazes. Its slow phase moves the eyes away from the desired target, while its fast phase makes the correction back to fixation. Gaze-evoked nystagmus is commonly seen in cerebellar disease, muscle palsy, alcoholism and drug toxicity.
Our patient also exhibited bilateral gaze palsy, which is defined as the inability to move the eyes either horizontally or vertically. Acquired horizontal gaze palsy is usually due to abnormalities in the pons often due to CVA, although other causes include myasthenia gravis, multiple sclerosis, systemic lupus erythematous, syphilis and Wernicke’s encephalopathy. The main differential diagnoses for our patient were small pontine stroke or WE. His MRI findings showed no abnormalities consistent with CVA. In addition, he showed no other signs or symptoms of stroke, including one-sided numbness or paresis to extremities, ataxia, vertigo or difficulty swallowing. The patient did suffer from gait difficulties that he attributed to osteoarthritis; however, these were longstanding and did not acutely worsen during the diplopic episode.
Cerebellar lesions such as those caused by a stroke are most often responsible for acquired nystagmus. The cerebellum is responsible for optimizing ocular motor function in order to bring the target to the fovea and to maintain foveal fixation. Cerebellar stroke can impair gaze holding, leading to a gaze-evoked nystagmus and other symptoms such as headaches (common), nausea, vomiting, vertigo, truncal and appendicular ataxia (inability to move truck and extremities of the body); any associated motor defects will be ipsilateral.
Our patient’s CT and MRI findings were unremarkable for acute abnormalities, but did show prominent cerebellar global atrophy with questionable symmetrical aqueductal FLAIR hyperintensity. Cerebellar degeneration can be associated with gait difficulties and restrictive ocular motility, such as nystagmus. In addition, patients with WE may demonstrate a higher degree of cerebellar atrophy. Our patient underwent a second MRI study with thinner cuts, and detectible structural abnormalities were evident.
We followed up with our patient in conjunction with our neuro-ophthalmology clinic at 1 month and 3 months after his initial visit. He denied any further episodes of double vision after beginning thiamine treatment. He continued to deny any headaches, nausea/vomiting, vertigo or other systemic symptoms. These are important negatives even in the context of normal brain scans. He continues to have gait difficulties, but they have improved with physical therapy.
The patient continued to have residual end-gazed nystagmus at the 1-month visit, but it had improved. At the 3-month follow-up, the patient only had slight end-gaze nystagmus in left gaze; it was absent in all other gazes. He continues to be followed by neurology and is currently taking multivitamins and low-dose aspirin at their recommendation. We will follow up with him again in 4 to 6 months.
- References:
- Bradley WG, et al. Neurology in Clinical Practice: Principles of Diagnosis and Management. U.K.:Butterworth-Heinemann Ltd.; 200
- Martin P, et al. The role of thiamine deficiency in alcoholic brain disease. National Institute on Alcohol Abuse and Alcoholism. https://pubs.niaaa.nih.gov/publications/arh27-2/134-142.htm. Posted July 2004. Accessed May 15, 2017.
- Nishimoto A et al. In Vivo. 2017;31:121-124; doi: 10.21873/invivo.11034.
- Stahl J, et al. Arch Ophthalmol. 2000;118:544-549; doi:10.1001/archopht.118.4.544.
- Wright J et. al. Stroke. 2014;45:e56-58; doi.org/10.1161/STROKEAHA.114.004474.
- Zuccoli G, et al. Am J Neuroradiol. 2009;30:171-176; doi.org/10.3174/ajnr.A1280.
- For more information:
- Abby Raposo, OD, is a New England College of Optometry ocular disease resident at the VA Medical Center in Providence, R.I. She can be reached at VAMC Providence Eye Clinic, Providence, R.I.; abby.raposo@va.gov.
- John Sellechio, OD, is a staff optometrist at the VA Medical Center in Providence and is in private practice in Warwick, R.I. He is clinical instructor of optometry with the New England College of Optometry and affiliated clinical professor of optometry with both the Illinois College of Optometry and Midwestern University. He can be reached at VAMC Providence Eye Clinic; john.sellechio@va.gov.
- Edited by Leo P. Semes, OD, FAAO, a professor of optometry, University of Alabama at Birmingham and a member of the Primary Care Optometry News Editorial Board. He may be reached at lsemes@uab.edu.
Disclosures: Raposo and Sellechio report no relevant financial disclosures. Semes is an advisor or on the speakers bureau for Alcon, Allergan, Bausch + Lomb, Genentech, Maculogix, OptoVue, Shire and ZeaVision. He is a stockholder with HPO.