Anesthetic management for a patient with Huntington disease

A 41-year-old man (169 cm, 48 kg), having a 10 year history of Huntington disease, was presented for percutaneous endoscopic gastrostomy because of repeated aspiration episodes. He had suffered from choreiform movements, misswallowing and progressive mental deterioration. Midazolam 2 mg i.v. was given on transferring the patient to the operating room. On arriving, the patient was somnolent but responded to call. BIS index was 55. Anesthesia was induced with thiopental 120 mg i.v. and fentanyl 100 microg i.v. followed by vecuronium 4 mg i.v. After tracheal intubation, anesthesia was maintained with sevoflurane 1.5% in 33% oxygen. Bispectral index and train of four ratio were monitored throughout the anesthesia. BIS index and TOF ratios were proper for the drug dose used. At the end of the procedure, neuromuscular blockade was antagonized with neostigmine 2.0 mg and atropine 1.0 mg i.v. with no worsening of symptoms. The duration of anesthesia was 85 minutes. The patient woke up (BIS index 78) and spontaneous respiration returned and he was extubated. The postoperative course was uneventful. In this case, BIS index was abnormally low before induction of anesthesia as well as after anesthesia. Whether Huntington disease is responsible for the abnormally low bispectral index remains uncertain. But, anesthesiologists should be aware of this phenomenon to avoid an inappropriate adjustment of the anesthetic depth.