Not Just Drunk- Wernicke's Encephalopathy in the ED

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Wernicke’s Encephalopathy (WE) is a difficult disease to recognize and a hard diagnosis to make. The reason for this is many fold, but likely has to do with the population most susceptible to this- the chronic alcohol (ETOH) misuser. [Note- while we recognize the term alcoholic may be considered outdated by some, for simplicity this term will be used from here forward].

As we all learned in medical school, the classic triad of WE is altered mental status, ataxia, and ophthalmoplegia. This triad is, of course, rare in the clinical setting (10-30%).[1,2,3] As we all know, the chronic alcoholic often has many of these symptoms simply related to their alcohol use or intoxication when we see them in the ED. This likely leads to WE being masked by alcohol intoxication or under recognized in a population that regularly gets overlooked in the ED. It is no surprise, then that 12.5% of alcohol abusers had WE lesions on autopsy. [2]

Epidemiology and Pathophysiology

Interestingly, WE is more common in men, but women are more susceptible. This again likely has to do with the higher proportion of men who have chronic alcohol abuse tendencies. It is by far most common in alcoholics (90% of all cases), but also can be seen in hemodialysis patients (thiamine is a water soluble vitamin), patients with eating disorders, HIV/AIDS patients, and bariatric surgery patients to name a few. Recognizing the disease in these other populations, however, is often less challenging.

The deficiency in thiamine is felt most in the highly metabolically active areas of the body, in particular the brain, where thiamine serves a role in energy metabolism and enzyme function. A deficiency leads to neuronal injury and causes petechial hemorrhages in several areas of the brain, most notably the mamillary bodies. The injury pattern is classically symmetric in nature.

Manifestations in the Alcoholic

If we think about the traid of WE- altered mental status, ataxia, and ocular abnormalities, and hold those symptoms up against a list of the manifestations of alcohol misuse and intoxication, we see more similarities than differences. In truth, when we build a Venn Diagram of the disease processes, there is far more overlap than not. Therefore, we are looking for little cues and differences to raise our red flags or suspicion. Let’s break down each component of the triad and see if it helps clinch the diagnosis.

ALTERED MENTAL STATUS

The altered mental state of WE vs that of alcohol intoxication is very difficult if not impossible to parse out. There are only two things in AMS that can help us:

1. Time: The altered state of acute alcohol intoxication, as we all know (some from experience) is short lived. WE and its altered state will not improve over hours like alcohol intoxication.

2. Pattern recognition: We get it, you don’t want to watch all of your chronic alcoholics in the department until they start withdrawing to assure yourself they don’t have WE. To that end, we know our frequent presenters well, we know their intoxication well. If they are presenting differently than than normal intoxication, raise the red flags and maybe dig deeper.

ATAXIA

The ataxia of WE is said to be more of a truncal process. To that end, ataxia of the extremities and dysarthria are uncommon in WE and very common in alcohol intoxication.[2] While it is difficult to hang your hat on this difference, it is again one of the little cues that says this is more than just alcohol intoxication.

OCULAR ABNORMALITIES

So far things have been a bit grim. Maybe if we’re lucky (and astute) we notice a difference in the confusion of our chronic alcoholic. Or maybe we notice their coordination is awry. But there is very little hard evidence to grab on to here. Luckily, the eyes may hold the key. There are several possible manifestations of ocular abnormalities for WE. Let’s look at each.

Nystagmus

Nystagmus is a very common finding in WE at 85%.[4] Unfortunately, as we all know, it is also common in the acutely intoxicated. That said, much like AMS, we should know (or come to learn) if our chronic alcoholics manifest nystagmus as part of their intoxication. If they don’t usually, then one day they do… red flag.

Palsies

Gaze palsies seem to be where the money is in differentiating the ocular abnormalities of WE from acute alcohol intoxication. Bilateral rectus palsies (right eye won’t look right, left eye wont look left) can be seen in up to 54% of patients. Conjugate gaze palsies can also be seen in 45% of patients.[4] Therefore, if there are any palsies seen, (essentially an eye or eyes not looking where they should) suspicion for Wernike’s should be heightened.

OTHER TIP OFFS

There are other signs and symptoms to WE that are unique and should trigger increased concern. In particular, hypothalamic dysregulation manifesting as hypothermia and hypotension, in an at-risk person such as an alcoholic, should raise red flags for WE.[3]

DIAGNOSIS

Unfortunately, WE is a clinical diagnosis. There are no specific labs or tests that can clinch the diagnosis. A low thiamine level (by high performance liquid chromatography) can increase your post-test probability, but a normal level does not rule out the disease.[4]

If the patient is getting an MRI for another reason (we would not recommend a MRI to rule-out WE, keep reading) and the study shows symmetric bilateral disease of the mamillary bodies, periventricular regions, midbrain, among others, think WE.[2] The test characteristics, however, are quite poor with a 53% sensitivity but a reasonable specificity at 93%.[4] MRI, therefore, can help rule in but not rule out WE.

THE ACE UP OUR SLEEVES

Much of what we have outlined here has been relatively discouraging- the AMS of WE is hard to differentiate from acute alcohol intoxication unless you know the patient well, the ataxia is very hard to flesh out, nystagmus has a strong overlap between the diseases, thiamine levels are helpful, and there is no radiologic test we can hang our hat on. There are, however, little diamonds we can pluck from the rough- the ataxia of WE is more central and less likely to include limbs and dysarythria, gaze palsies are more common in WE and not seen in alcohol intoxication, and MRI if positive is very specific.

In the end we have one more ace up our sleeves… and that is time. If you have any red flags from what we just went over or the patient needs to stay for some other reason (head trauma requiring a sober neuro exam, cold night where you can’t discharge them, etc.) take the time to do a good neuro exam. Again, alcohol intoxication clears and Wernicke’s doesn’t. Don’t fear the withdrawal, we are good with benzos and can dose them easily to meet our patient’s needs. This at risk population needs and deserves our time and attention. If you’re conscientious and careful, the little extra time you spend on this can help protect a volunerable person from a bad outcome.

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References

1.     Flynn A, Macaluso M, D'Empaire I, Troutman MM.  Wernicke's Encephalopathy: Increasing Clinician Awareness of This Serious, Enigmatic, Yet Treatable Disease. Prim Care Companion CNS Disord. 2015 May 21;17(3). [pubmed]

2. So Y. “Wernicke Encephalopathy.” https://www.uptodate.com/contents/wernicke-encephalopathy. Jan 2020.

3. Thomson A, Cook C, Touquet R, Henry JA, Royal College of Physicians, London. The Royal College of Physicians report on alcohol: guidelines for managing Wernicke's encephalopathy in the accident and Emergency Department. Alcohol Alcohol. 2002 Nov-Dec;37(6):513-21. [pubmed]

4.   Donnino MW, Vega J, Miller J, Walsh M. Myths and misconceptions of Wernicke's encephalopathy: what every emergency physician should know. Ann Emerg Med. 2007 Dec;50(6):715-21. Epub 2007 Aug 3. [pubmed]