Dopamine agonists increase perseverative instrumental responses but do not restore habit formation in a rat model of Parkinsonism.

Dopamine (DA) deafferentation of the dorsolateral striatum has been shown to prevent habit development, leaving instrumental behavior under action-outcome control that is persistently sensitive to modification of the motivational value of the reward. The present experiment further explored the basis of this dysfunction by examining the ability of intrastriatal DA agonist injections (D1 SKF 38393 or D2/D3 Quinpirole) during overtraining of a signaled instrumental task to restore habit formation in rats subjected to bilateral 6-hydroxydopamine (6-OHDA) lesions of the nigrostriatal dopaminergic pathway. Overtraining was followed by a test of goal sensitivity by satiety-specific devaluation of the reward. The results confirmed the impaired shift in performance from action to habit in control lesioned rats. However, lesioned rats repeatedly injected with quinpirole D2/D3 agonist showed an increase in non-rewarded instrumental responses (intertrials periods) during overtraining, suggesting the development of perseverative behavior. Following the procedure of devaluation, quinpirole D2/D3 agonist treatment, and to a lesser extent SKF 38393 D1 agonist, caused the persistence of sensitivity to reward devaluation, indicating clear goal-directed behavior despite extended training. This absence of restoration of habit formation by DA agonist treatment is discussed in the light of DA agonist effects in Parkinson patients.

[Chronic tinnitus and hearing loss caused by cerebrospinal fluid leak treated with success with peridural blood patch. Apropos of 2 cases]. / Acouphènes chroniques et hypoacousie secondaires à une fuite de liquide céphalorachidien guéris par blood patch péridural. A propos de deux cas.

Hearing loss and tinnitus are frequently encountered in ENT patients and usually require complementary investigations such as audiogram, auditive evoked potentials, CT scan, MRI... One recent etiology, that is more and more discovered, is a decrease in spinal fluid pressure secondary to a dural fluid leak that occurs after a diagnostic lumbar puncture, a spinal anesthesia, an accidental dural puncture during an epidural technique or a lumbar myelography. Postural headache which are frequently present in such a setting, may mask these auditive symptoms. Epidural injection of autologous blood (blood patch) performed by anesthesiologists, which is usually indicated to treat such postural headaches, is efficient in relieving other symptoms related to spinal fluid leak after dural puncture. We report two cases of isolated auditive complaints (hearing loss and tinnitus) which have been dramatically improved after blood patch. In conclusion, ENT surgeons should seek for a recent or even a past history of spinal puncture whenever the etiology of auditive symptoms of their patient remains unclear.

[A traditional anesthesia consultation or a "telephone interview" within the framework of ambulatory surgery?]. / Consultation d'anesthésie traditionnelle ou "interview téléphonique" dans le cadre de la chirurgie ambulatoire?

UNLABELLED: Preoperative assessment for anaesthesia must detect in the setting of ambulatory surgery both medical and sociopsychologic problems which may contraindicate the ambulatory aspect of the procedure. The goal of our prospective study was to assess the efficacy of a preoperative telephone interview in screening the medical and sociopsychologic problems of ambulatory patients. 1,000 consenting consecutive outpatients participated to the study and were randomly allocated to one of two groups: patients in the standard group (STD) had a consultation a few days before surgery whereas those in the telephonic group (TEL) called the anesthetist a few days before, the physical exam being performed on the day of surgery. The cancellation of the ambulatory procedure was decided upon either medical criterias (MC) or sociopsychologic criterias (from Waetchler). RESULTS: both groups were comparable regarding SPC and MC but prescription of preoperative tests was more frequent in the STD group (result statistically significant). In conclusion, this new approach is as reliable as the standard consultation in screening the SPC which remain the most frequent cause of cancellation in ambulatory surgery. Therefore this telephonic interview which is simple and reliable for screening outpatients may represent a suitable alternative to a standard consultation.

Reversal of hypoxia-induced decrease in human cardiac response to isoproterenol infusion.

A decrease in heart rate response to isoproterenol (IP) infusion has been previously described in humans exposed to acute (2-3 days) or chronic (21 days) exposure to altitude hypoxia (J. Appl. Physiol. 65: 1957-1961, 1988). To evaluate this cardiac response in subacute (8 days) hypoxia and to explore its reversal with restoration of normoxia, six subjects received an IP infusion under normoxia (condition N), after 8 days in altitude (4,350 m, condition H8), on the same day in altitude after inhalation of O2 restoring normoxic arterial O2 saturation (SaO2, condition HO), and 6-11 h (condition RN) and 4-5 mo (condition ND) after the return to sea level. Cardiac chronotropic response to IP, evaluated by the mean increase in heart rate from base value (delta HR, min-1), was lower in condition H8 [mean 30 +/- 13 (SD)] than in condition N (50 +/- 14, P less than 0.03); it was slightly higher in condition HO (38 +/- 14) or condition RN (42 +/- 15) than condition H8 but still significantly different from condition N (P less than 0.03), despite normal values of SaO2. delta HR in condition ND (55 +/- 10) returned to base N value. These findings confirm the hypothesis of a hypoxia-induced decrease in cardiac chronotropic function. Two possible mechanisms are suggested: an O2-dependent one, rapidly reversible with recent restoration of normoxia, and a more slowly reversible mechanism, probably a downregulation of the cardiac beta-receptors.