LETTERS TO THE EDITOR

Wernicke's encephalopathy after gastrectomy due to thiamine deficiency

Encefalopatía de Wernicke en pacientes tras gastrectomía por deficiencia a la tiamina

Key words: Wernicke's encephalopathy. Beri-beri. Thiamine.

Palabras clave: Encefalopatía de Wernicke. Beri-beri. Tiamina.

Dear Editor,

Wernicke's encephalopathy (WE) is an acute neuropsychiatric syndrome resulting from thiamine (B1 vitamine) deficiency, whose treatment is parenteral thiamine administration. Allergic reactions are rare. We present a WE case in a patient with suspicion of a thiamine allergy who was a challenge to manage and treat.

Case report

A seventy-three years old female patient was treated with chemotherapy and a subtotal gastrectomy for gastric cancer. She had a previous history of suspected allergy to vitamine B (Neuromade^®). She developed a postoperative gastrojejunal fistula which was managed conservatively with NPO and TPN, and without thiamine. During the first few weeks the patient developed increasing mental status changes with disorientation, slow mentation, drowsiness, lateral nystagmus and ocular motor abnormalities, all of which led to the suspicion of thiamine deficiency. She underwent a thiamine allergy skin test in an intensive care setting, which proved negative, and was subsequently treated with i.v. thiamine with a complete reversal of neurologic symptoms.

Discussion

Thiamine is a water-soluble vitamine which is absorbed in the duodenum. Food intake is the principal source of thiamine. The body storage of thiamine is low and it is concentrated mainly in the muscle, where the level reaches 30 mg (1).

Thiamine deficiency is, most of the times, related to an insufficient food intake, and symptoms usually appear after two weeks without any intake. The resulting central neurological syndrome is known as Wernicke's encephalopathy (WE). It was first described by Carl Wernicke in 1881, and characterised by the classical triad of: ocular motor abnormalities, ataxia and mental status changes (only 20% of the patient present the triad). Most of the patients also present disorientation and apathy (1,2).

We remains a clinical diagnosis which can be confirmed by determining blood or urine thiamine concentrations; MRI is considered as the most valuable adjunct for diagnosis. Therefore, a differential diagnosis with other possible causes of acute encephalopathy like paraneoplastic encephalitis, limbic encephalitis, ACVA, hypoosmolar states (severe hypophosphataemia, hyponatremia, etc.) is always warranted (3,4).

Treatment should be initiated immediately with parenteral thiamine for a minimum of 5 days, or until an adequate intake can be assured. Thiamine should be added to TPN solutions if the patient is not going to receive it from other sources for longer than one week, since the high glucose content of TPN means a quicker depletion of the body storage of the vitamin. The response of symptoms to parenteral thiamine is a sequential one: ocular motor abnormalities, ataxia and, finally, drowsiness, apathy and confusion. Nystagmus is generally persistent.

Allergic reactions to group B vitamines are rare, and have been reported as isolated cases since 1938. Parenteral thiamine administration is generally safe as demonstrated by Wrenn et al., who reported on a retrospective study including 300.000 patients treated, without any significant allergic reactions. Although the pathophysiology remains unknown, a hypersensitivity mechanism could be involved following its parenteral administration. The diagnosis should be confirmed by means of a skin test with a thiamine dose of 1 mg/ml (5,6).

The treatment of thiamine allergy depends on the symptoms, and anaphylactic shock treatment includes facilities for cardiopulmonary resuscitation and intravenous or intramuscular adrenaline. Immunotherapy is advocated in patients with proven allergy, with increasing doses of up to 100 mg/ml per day, during several days without any allergy reactions and with a negative skin test (6).

Our patient had several risk factors for WE (gastrectomy, prolonged TPN without thiamine). A pre- or immediately post-operative skin test would probably have prevented the development of symptoms.

We believe that a skin test is warranted in patients with a suspicion of thiamine allergy and who have risk factors for WE. If the skin test is positive, immunotherapy with progressive doses of thiamine is appropriate.

T. Sánchez Rodríguez, A. García Marín, C. Camarero Mulas, M. Sanz Sánchez and F. Turégano Fuentes

Service of General Surgery and Digestive Diseases II. University Hospital Gregorio Marañón. Madrid, Spain

References

1. Sechi G, Serra A. Wernicke's encephalopathy: new clinical settings and recent advances in diagnosis and management. Lancet 2007; 6: 442-5.        [ Links ]

2. 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; 50: 715-21.        [ Links ]

3. Storstein A, Bru A, Vedeler CA. Limbic encephalitis - a diagnostic challenge. Tidsskr Nor Laegeforen 2007; 127: 3077-80.        [ Links ]

4. Weidauer S, Nichtweiss M, Lanfermann H, Zanella FE. Wernicke`s encephalopathy: MR findings and clinical presentation. Eur Radiol 2003; 13: 1001-9.        [ Links ]

5. Wrenn KD, Slovis CM. Is intravenous thiamine safe?. Am J Emerg Med 1992; 10: 165.        [ Links ]

6. Mitrani M. Vitamin B1 hypersensitivity with desensitization: report of a case. J Allergy 1944; 15: 150-3.        [ Links ]