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Is euphoria a side‐effect of lidocaine?

2004; Wiley; Volume: 59; Issue: 12 Linguagem: Inglês

10.1111/j.1365-2044.2004.04025.x

1365-2044

Ahed Zeidan, A Baraka,

Plant-based Medicinal Research

Lidocaine is widely used for local and regional anaesthesia. It is also administered intravenously to control ventricular arrhythmias. The main systemic side-effects of lidocaine are dizziness, drowsiness, coma, seizures, respiratory arrest, muscle twitching, paresthesia, dysarthria, numbness of the tongue, tinnitus, diplopia and other visual disturbances. We report an unusual side-effect which followed lidocaine administration in two patients. A 24-year-old man, ASA I, with no history of epilepsy or CNS disease, was admitted for wound repair of the left forearm. An axillary block was performed using 35 ml lidocaine 2% without epinephrine. A blood aspiration test was negative. However, after 2 min the patient became talkative and developed a ‘high state of happiness’; he started to laugh, sing and tell jokes. Shortly afterwards, the patient complained of severe tinnitus, diplopia and tongue numbness. The euphoria lasted for about 40 min. The next day, the patient recalled the ‘wonderful pleasant experience’ but was unable to recall the exact details. A 56-year-old man was admitted for right femoro-popliteal endarterectomy under local anaesthesia. After infiltration of 50 ml lidocaine 1%, he developed an unexplained feeling of exaggerated happiness. The patient started to laugh and tell jokes. He also reported tinnitus and numbness of the tongue. This euphoric state lasted 50 min. The next day, the patient stated ‘I was like a drunken man’. Psychotic reactions have been reported after intravenous lidocaine administration to control ventricular arrhythmias [1]. Most reactions are about fear from death, doom anxiety and delirium [2]. However, euphoria is rarely reported. Blanke et al. described a short-lasting euphoria after intravenous lidocaine in a patient who was addicted to cocaine [3]. The euphoric properties of cocaine are due primarily to inhibition of catecholamine reuptake at CNS synapses. Other local anaesthetics do not block the uptake of norepinephrine. Our patients denied any history of cocaine or alcohol abuse. The euphoric effect of lidocaine can be attributed to its central action. Anaesthetists usually ask about tinnitus, vision alterations, metallic taste and tongue numbness to detect early evidence of lidocaine toxicity. Mood changes may pass unrecognised if the patient's personality is unknown to the physician, the behaviour is considered the result of a psychotic personality; or if the behaviour is masked by premedication or sedatives. In summary, it is possible that mood alterations, especially euphoria, may be an early sign of CNS reaction following lidocaine administration.