Hyperventilation syndrome: clinical, ventilatory, and personality characteristics as observed in neurological practice.

The symptoms of the hyperventilation syndrome (HVS) are sometimes diffuse, and HVS may resemble other clinical conditions. A diagnosis of HVS was made in 25 patients referred for neurological assessment because of atypical, shortlasting, episodic complaints. The referral diagnoses varied within a wide range. A need for more indepth knowledge about this group of patients thus arose. During a provocation test with forced respiration, all patients reported symptoms similar to those during attacks. Eight patients described numbness or paraesthesias with unilateral predominance. End-tidal pCO2 levels were monitored prior to and during a forced hyperventilation test. Compared with controls, the patients had significantly decreased end-tidal pCO2 even during symptom free periods. After hyperventilation, hypocapnia followed a protracted course in the patient group. Sensory symptoms may be asymmetric and mimic focal cerebral disease. Strained respiration may be denied during spontaneous attacks. Personality characteristics were evaluated with the Minnesota Multiphasic Personality Inventory (MMPI). A mean group profile very similar to profiles reported on "pseudoepileptic" patients was found. The profile indicates a neurotic pattern where patients tend to respond to psychological stress with somatic symptoms.