The Argyll-Robertson pupil is absent. The gait is the steppage one of peripheral neuritis, the patient walking as if extracting one foot after the other from clinging mud. Later on, when other muscles than the foot extensors are involved, the gait becomes a shuffling one. The mind is entirely clear. The vasomotor phenomena are often marked as shown by patchy or most extensive development of oedema and serous exudates. The knee-jerk is usually absent. Fibrillary twitchings may be observed in beriberi as well as in progressive muscular atrophy. The extensors of arms and legs are more markedly affected than the flexors. The cardiac symptoms are really connected with vagal involvement.
The Cardio-respiratory Symptoms.—Owing to involvement of the vagus the inhibitory apparatus is deranged so that we have palpitation and rapid pulse rate both of which are markedly increased by the slightest exertion.
The blood pressure is below normal. Shortness of breath is the earliest feature of respiratory trouble. This may go on to marked thoracic oppression and dyspnoea.
Aphonia may be present in acute pernicious beriberi and probably indicates laryngeal palsies. Such cases are usually fatal.
Pulmonary congestion and oedema always accompany the terminal right side dilatation of the heart which is responsible for the cyanosis, pulsating jugulars and various murmurs. The pulmonic second sound is accentuated and may be reduplicated. The rhythm of the heart sounds is replaced by the equal spacing of embryo-cardia. The diaphragm may be paralyzed as may also happen to the intercostal muscles.
Digestive and Urinary Symptoms.—Those who considered beriberi as an acute infectious disease were disposed to note frequently evidences of toxaemia as manifested by nausea, vomiting and epigastric distress. As a matter of fact these symptoms only become very prominent in pernicious beriberi and may well be connected with the cardiac decompensation. However caused vomiting is of unfavorable prognostic import.
The amount of urine is markedly decreased when oedema is advancing but is succeeded by a polyuria when this diminishes. If albumin should be present it is not connected with beriberi but some other condition.
Other Features.—There is nothing characteristic about the blood other than a slowly developing anaemia.
Oedema is the most striking feature of wet beriberi. When slight this oedema may only involve the pretibial-region or sternum. Circumscribed areas of oedema may be present on the upper parts of the body as neck and trunk.
Hydropericardium is the most frequent of the exudates into serous cavities. Fever is almost always absent except in epidemic dropsy.