Abstract
Dear Sir We report a cephalalgia induced by accidental nitric acid (HNO3) inhalation. When HNO3 is in contact with brass or copper, as during metal polishing, chemical reactions occur that lead to the formation of nitric oxide (NO) and NO2. NO is able to induce several forms of headache. When inhaled, NO2 produces a damaging action, especially at a pulmonary level (1–4).
On September 2000 we had under our observation a goldsmith from the Department of Emergency Assistance (DEA). He was 65 years old, admitted because of an acute respiratory intoxication and headache attack resistant to common pharmacological treatment.
His parents suffered from migraine and he himself had suffered from ‘migraine without aura’ with presence of vomiting and nausea every month since he was 12 years old.
HNO3 is used as metal polish, and our patient, when exposed at work to HNO3 vapour inhalation, experienced migraine every day. There was a clear correlation between HNO3 vapour inhalation and headache attacks. Furthermore, during weekends he was headache free and during vacations he suffered from headaches only sporadically. The crises after HNO3 vapour inhalation were therefore clearly connected to migraine without aura. About 5 min after exposure, there was a sudden painful and beating attack in the front orbital area together with nausea and/or vomiting, phono- and photophobia and lachrymation.
Non-steroidal anti-inflammatory drug therapy gave little relief because the attacks lasted from 12 to 24 h. The headaches responded instead to triptans. With this treatment, attacks stopped in about 20 min or, continuing in rare episodes, they disappeared after a second dose (5). On admission to hospital a computed tomography examination was made. When the patient was headache free, other examinations were: magnetic resonance, electroencephalogram, sight and hearing. All were normal. Transcranial Doppler was normal both during attacks and in absence of pain.
Many migraine without aura attacks were connected to NO inhalation; in fact, when the patient was not exposed to HNO3 the attacks had a monthly frequency. His attacks were controlled with triptan therapy given sublingually.