Beriberi

Beriberi is a syndrome that combines, to varying degrees, a sensory-motor polyneuropathy and a (sub)acute onset dilated cardiomyopathy. Relatively common (now rare in developed countries), it is usually the result of a thiamine (vitamin B1) deficiency and is primarily seen in severely malnourished individuals in developing countries. In developed countries, it has become rare and is mainly encountered in alcoholics, those on very restrictive diets, and post-bariatric surgery patients.

It arises from the same etiologies and pathophysiological processes as Wernicke's encephalopathy. The syndromic separation of Wernicke's and beriberi is mainly due to historical reasons and can lead to medical errors. Clinicians should consider them as the same pathological entity. Thus, readers are referred to the article on Wernicke's encephalopathy for these chapters.

Clinical

Although beriberi is traditionally divided into two forms, "dry" (predominance of polyneuropathy) and "wet" (predominance of cardiomyopathy), the key determinant of mortality in this condition is the progression of cardiomyopathy.

"Dry Beriberi"

The clinical picture is dominated by subacute sensory-motor polyneuropathy, associated with neuropathic pain (++ burning sensations) in the extremities, distal weakness, and balance disturbances.

"Wet Beriberi"

The clinical picture is dominated by dilated cardiomyopathy, typically resulting in high-output heart failure (ultimately, all heart failure becomes low-output) with very suggestive features:

• Tachycardia even at rest, dyspnea, peripheral edema
• Bounding pulse, Traube's sign (double tapping sound on femoral auscultation), jugular murmur on auscultation, accentuated first heart sound, mid-systolic murmur, third heart sound

Association with Wernicke's Encephalopathy

The central nervous system is far more sensitive to the metabolic consequences of vitamin B1 deficiencies, making Wernicke's encephalopathy much more common than beriberi.

During a Wernicke's episode, true beriberi is rare, although cardiovascular anomalies (arrhythmias, increased cardiac output, dyspnea, various ECG abnormalities, etc.) are common. Conversely, in beriberi, the association with Wernicke's encephalopathy is frequent and is obviously a worsening factor.

Differential Diagnosis

The differential diagnosis primarily involves high-output heart failure: obesity, arteriovenous fistulas, cirrhosis, erythroderma, carcinoid syndrome, myeloproliferative disorders, hyperthyroidism, sepsis, acromegaly, anemias, COPD.

Additional Examinations

Electromyography and nerve conduction studies (EMG-NCV) for polyneuropathy have limited diagnostic utility. First, because the electrophysiological abnormalities of beriberi polyneuropathy may take several weeks to appear. Second, because in alcoholic patients, a chronic sensory-motor polyneuropathy is generally already present.

The fundamental examination is echocardiography, which confirms high-output heart failure. Invasive hemodynamic studies should be considered on a case-by-case basis.

In cases of diagnostic doubt, laboratory tests (TSH, T4, complete blood count, renal and liver functions) and hepatic ultrasound should be performed.

Treatment - Therapeutic

Management Management consists of vitamin supplementation and supportive care for heart failure.

Bibliography

Bradley WG et al., Neurology in clinical practice, 5th ed., Butterworth-Heinemann, e-dition, 2007

EMC, Traité de médecine AKOS, Elsevier, 2018

Givertz M et al, Causes and pathophysiology of high-output heart failure, UpToDate, 2022

UpToDate, Vitamin deficiency syndromes and dietary sources of common vitamins, UpToDate, 2022