Autonomic dysfunction and SIADH as first signs of Guillain-Barre syndrome

A 68-year-old woman was admitted to our Internal Medicine Unit for severe hyponatremia and new onset resistant hypertension for two weeks. She also complained of nausea, weakness and paresthesia of the limbs in the previous 4 days. Several diagnostic tests were performed (blood, hormonal and urinary tests, echocardiography, ECG, renal arteries Doppler-US, total body CT scan), showing only severe hyponatremia, mild hypokalemia and mild hypochloremia. Hypertension was treated with isosorbide and doxazosin, whereas in the suspect of a Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH), hyponatremia was treated with hypertonic saline solution with progressive normalization of serum sodium levels. Despite improvement in the presenting symptoms, after 10 days the neurological scenario worsened, with persistence of weakness and onset of areflexia of lower limbs, constipation and urinary retention. Therefore, the patient was evaluated by a neurologist who, hypothesizing a Guillain-Barre Syndrome (GBS), required an EMG, which confirmed this clinical suspect. Intravenous immunoglobulins were immediately started and administered for 5 days, with partial improvement of weakness and areflexia. The patient was then transferred to a rehabilitation institute for the recovery path. We report a rare form of GBS where hypertension and SIADH, not frequent clinical features of this acute inflammatory polyneuropathy, preceded the neurological manifestation. In fact, the delay in the manifestation of the neurological pattern made harder and delayed the diagnosis. However, it is important to stress that a high clinical suspicious should rise in presence of multi-resistant hypertension with, even mild, neurological symptoms and electrolytes disturbances.