Imaging-based diagnosis of wernicke encephalopathy: a case report.

INTRODUCTION: Wernicke encephalopathy (WE) is a medical emergency characterized by ataxia, confusion, nystagmus and ophthalmoplegia resulting from thiamin deficiency. Alcoholism is the common cause for this disease. CASE
PRESENTATION: A 41 year old man was brought to our emergency department (ED) complaining of confusion. One week earlier he had started to experience severe nausea and vomiting followed by diplopia, dysarthria and also dysphagia. One day later he had experienced gait disturbance and progressive ataxia accompanied with confusion, apathy and disorientation. He had no history of alcoholism, drug abuse or previous surgery but had history of untreated Crohn disease. Just before arrival to our emergency department, he had been hospitalized in another center for about a week but all investigations had failed to provide a conclusive diagnosis. Upon admission to our ED, he was dysarthric and replied with inappropriate answers. On physical examination, bilateral horizontal nystagmus in lateral gaze, left abducens nerve palsy and upward gaze palsy were seen. Gag reflex was absent and plantar reflexes were upwards bilaterally. After reviewing all the previously performed management measures, MRI was performed and was consistent with the diagnosis of WE. Treatment with thiamine led to partial resolution of his upward gaze palsy and nystagmus on the first day. At the end of the third day of treatment, except for gate ataxia, all other symptoms completely resolved and he was fully conscious. After the fifth day his gait became normal and after one week he was discharged in good general condition. DISCUSSION: After reviewing the current literature, it seems that brain MRI can be helpful in the diagnosis of WE in patients with the classic clinical trial in the absence of clear risk factors.

1. Introduction

Wernicke encephalopathy (WE) is a medical emergency characterized by ataxia, confusion, nystagmus and ophthalmoplegia which is related to an initially reversible biochemical brain damage resulting from the depletion of intracellular thiamine stores. Left untreated, it may lead to Korsakoff syndrome or even death (1, 2).

Alcoholism is the most common cause of thiamine deficiency around the world (3). Poor diet associated with unhealthy lifestyle, impaired thiamine storage, chronically compromised thiamine absorption from the gastrointestinal tract and reduced thiamine metabolism are some of the known etiologies of this condition (3-6).

2. Case Presentation

A 41-year-old man was brought to our ED complaining of confusion. One week earlier he had started to experience severe nausea and vomiting. These symptoms were followed by diplopia, dysarthria and also dysphasia. One day later he had experienced gait disturbances and progressive ataxia accompanied with confusion, apathy and disorientation. He had no history of alcoholism, drug abuse or previous surgery but had a history of untreated Crohn disease. Just before the arrival in our ED, he was hospitalized in another center for about one week but all investigations had failed to reveal the diagnosis. When he was admitted to our ED, he was confused and disoriented to time and place. He was dysarthric and replied with inappropriate answers. Cranial nerve examination showed bilateral horizontal nystagmus in lateral gaze, left abducens nerve palsy and upward gaze palsy. Pupils had normal size and normal light reaction. Gag reflex was absent. In motor examination, tone and force of muscles were normal, DTRs were +2 in all limbs. Plantar reflexes were upwards bilaterally. Sensory examination was normal. Bilaterally, finger to nose exam was abnormal and dysmetria was seen. After reviewing all previously performed investigations, MRI was performed which was consistent with the diagnosis of WE (Figures 1 and 2). Treatment with thiamine led to partial resolution of his upward gaze palsy and nystagmus on the first day. At the end of the third day of treatment, except for gate ataxia, all other symptoms were fully corrected and he was totally conscious. After the fifth day his gait became normal and after one week he was discharged in good general condition.

Figure 1.

MRI (FLAIR Sequences) Consistent With the Diagnosis of WE

Figure 2.

MRI (Coronal T2 Weighted Sequence) Consistent With the Diagnosis of WE

It should be mentioned that after recovery he denied any alcohol consumption but mentioned occasional use of Clonazepam. All other clinical settings related to WE described in previous reports were thoroughly ruled out, including malnutrition, history of gastrointestinal surgical procedures, unbalanced nutrition including staple diet of polished rice, chronic diarrhea, cancer, systemic diseases such as renal disease, hyperthyroidism, and chronic infectious febrile diseases, magnesium depletion, and use of drugs known for causing WE.

3. Discussion

Classically, thiamine deficiency causes lesions in tectal plate, thalamus, hypothalamic nuclei and periventricular nuclei which may result in WE’s cardinal signs of ataxia, nystagmus, ophthalmoplegia and confusion (7). Although alcoholism is the most common cause, other disorders may affect thiamine bioavailability or metabolism (Box 1) (1, 7, 8).

Box 1.

Clinically Relevant Causes of Thiamine Deficiency

Clinically Relevant Thiamine Deficiency
Alcoholism
AIDS
Malnutrition
Hunger strike
Hepatic disease
Orofacial cancers
Pyloric obstruction
Multiple organ failure
Magnesium deficiency
Gastric bypass surgery
Long term hemodialysis
Hyperemesis gravidarum
Gastrointestinal carcinoma
Prolonged parenteral therapy
Prolonged furosemide therapy
Anorexia and Anorexia nervosa
Inflammatory bowel disease (IBD)
Rapid parenteral carbohydrate loading
Chronic diarrhea or persistent vomiting
Infarction of the Mammillothalamic tracts

In spite of the fact that thiamine deficiency is possible in the context of inflammatory bowel disease (IBD) and has been reported with various manifestation in some case reports, IBD and WE do not have a clear association with each other (9, 10). Whenever WE is suspected based on the physical exam and history, high-dose parenteral thiamine should be administered as soon as possible to reduce the risk of progression to Korsakoff Syndrome (KS) or death (2). Neuroimaging has been used for many years by emergency physicians in various trauma, ischemic and hemorrhagic brain insults and cerebral venous thrombosis. So it may be helpful to review some special aspects of this (11, 12). Imaging with the aim of diagnosing WE has been used from 1970s. Ventricular enlargement, especially in the third ventricle, has been reported in previous studies using computed tomography (CT) scanning but could not detect any focal damage or edema (7). Magnetic resonance imaging (MRI), with its high sensitivity for water contenting tissues , have revolutionized the diagnosis of neurologic lesions not visible on CT. Tissues with high water content which are shown as hyperintense abnormal structures in T2-weighted late-echo sequences of brain MRI, can be a sign of edematous lesion of WE in alcoholics (7, 13). Reviewing the literature, show the most obvious imaging sign of acute WE is bilateral hyperintensity on late-echo MRI, generally happening in gray matter tissues of the mammillary bodies, anterior and medial nuclei of the thalamus, inferior and superior colliculi, periventricular gray matter and occasionally cerebellum; bilateral distribution of these findings may correlate with the clinical severity of the disease (14-18). Although the pons is rarely affected in WE, but there is some evidence regarding excessive fluid accumulation in the central pons of patients with alcoholic WE-KS, revealed by MR study examination of T2 relaxation time (19).

Introduction of the MRI fluid attenuated inversion recovery (FLAIR) sequence has significantly advanced diahnosis. FLAIR sequences have special ability to enhance the signal in edematous lesions (7). In one study, by evaluating six nonalcoholic cases of WE with FLAIR, hyperintense signals were seen in the tissues around the medial thalami, third ventricle, aqueduct, anterior ventricular caps and floor of the fourth ventricle; follow-up examination noted recovery in the four cases without cortical damage but not in the two cases with such damage (16). Magnetic resonance diffusion-weighted imaging (DWI) is another proven MRI technique for detection of WE brain lesions. The bright signal, representing high diffusive abnormalities, in the periventricular and thalamic tissues typically is compatible with WE diagnosis; despite this fact, one case study concluded that bright signal on DWI was caused by abnormally low diffusion in the cerebellum, so further studies are still needed (15, 20, 21). DWI-increased signal intensity in the affected brain regions, confirmed as decreased diffusivity with apparent diffusion coefficient (ADC) images, has been reported in two studies of acute WE (21, 22). Interpretation of DWI accompanied by ADC imaging for assessment of the water diffusion, has allowed characterization of a spectrum of WE lesions from early edematous high diffusivity through later atrophic low diffusivity (7). The presented patient was diagnosed as having WE based on typical brain MRI findings and response of neurological signs and symptoms to thiamine administration. Thus, it seems that brain MRI can be helpful in diagnosis of WE in patients with classic clinical triad of WE but in the absence of clear risk factors. This case report can be useful in designing future retrospective and prospective studies in this disease.