Breathing in sleep in a case of brainstem glioma

70 both slope and area in which the slope is the inverse of compliance and the loop area is the inverse of distensibility. With this method, we show that vagotomy increases the work of infusion (slope) and, therefore, of the loop area. That is, both compliance and distensibility decrease. Electrical stimulation of the cervical vagus following vagotomy and injection of atropine restores both the slope and the area of the hysteresis loop. These results confirm the existence of an important tonicallyactive vagal inhibitory innervation to the gallbladder. Further analysis of the hysteresis loop provides an explanation for the failure of conventional manometric methods to detect the influence of this regulatory pathway. We have used injection of nitric oxide (NO) synthase inhibitors, e.g., L-NAME, to determine the role of NO as the inhibitory transmitter. Injection of L-NAME does not mimic the effects of vagotomy. It tends to reduce the area of the hysteresis loop, suggesting that it is acting as a weak agonist of NO synthase, resulting in NO release. This is in contrast to studies we have recently completed (Pauletzki et al., Eur. J. Pharm., in press) in which LNAME was effective in abolishing NANC nerve mediated inhibition of the guinea pig sphincter of oddi. The inhibitory transmitter, therefore, remains to be determined. 36 A Mathematical Model for the Disorders of the Cyclic Oscillations of the Blood Flow in the Skeletal Muscle L. De Cart and A. Ghizzi

Department of lnternal Medicine, IRCCS Policlinico S. Matteo, 27100 Pavia, Italy, and lnterdisc. Center of SportMedicine and -Biology, University of Pavia, Pavia, Italy The rhythm of the oscillations of the blood flow in the skeletal muscle may be studied by means of the continuous registration of the tissular apparent thermal conductivity according to Grayson (at rest h : 1113)< 10-4 Cal'cm-l'°C-l's-1) by using a heated thermofluximetric needle of the type described by Hensel (thermocouple as thermosensible element) or of that by Casella (NTC thermistor). Both in experimental conditions (i.e., during intra-arterial infusion of epinephrine [Golenhofen]) and in the clinic (in subjects with severe chronic anaemia or with Raynaud's syndrome [De Cart]) it has been observed that the sympathetic activation yielded an amplitude increase of the basal spontaneous oscillations of skeletal muscle's blood flow with a significant slowing of their frequency (one oscillation every 2 min instead of l/min). We developed a mathematical model that allowed us to reproduce the slowing down of frequency of the rhythmic oscillations in the peripheral circulation due to the increase of the neurotransmitter reaching the specific receptors of the smooth perivascular

muscle. The mathematical simulation is based on the trends of 'restricted' cumulative sums of random numbers, that one can get by adding up each random number to one, two, five or ten number immediately preceding. Our model allows us to explore and to compare situations with different levels both for the concentrations of neurotransmitter at the site of the receptors and for the length of the memory of the system. It respects the plasticity of the system's memory more than models based on the original 'cumulative sum' technique such as described by Woodward and Smith. 37 Breathing in Sleep in a Case of Brainstem Glioma G. Della Marca, E. Russo, G. Scivoletto. M.A. Petrella and G. Mennuni

Institute of Neurology, Catholic University, Rome, ltaly V.L., a 44-year-old male patient, affected by a neoplastic lesion located in the brainstem, has been submitted to two consecutive polygraphic recordings of spontaneous nocturnal sleep, in order to study the characteristics of his nocturnal breathing activity. Neuroradiologicat evaluation (MRI, CT scan) had previously documented an expansive-infiltrative process, with a cystic component, placed in the upper medulla and spreading in the whole brainstem, to the thalamus and the cerebellar hemispheres. These findings allowed to suspect the diagnosis of Glioblastoma Multiforme, which was confirmed by the postmortem neuropathological observations. Our patient, which was eupneic during active wakefulness, showed during relaxed wakefulness a typical periodic breathing pattern, with periods of hyperventilation lasting about 15-20 seconds, separated by central apneas of the same length. This respiratory pattern persisted along all NREM sleep stages, and was replaced, at the onset of each REM phase, or in the immediately previous minutes, by a fairly regular respiratory activity. A breathing pattern of this kind has been reported in literature in cases of brain hemispheric lesions, heart failure, or paraphysiologic conditions like sleep at high quote. These findings allow to discuss the mechanisms of breathing control during sleep.

38 Clinical and Cardiovascular Features of Parkiasen's Disease with Anteaelak Ftdlwe ( ~ A e H y p e t e a s i e a ) M. De Marinis, K. Bteasd~e and C.J. Mathias Autonomic Unit, The National Hospital for Neurology and

Neurosurgery, Queen Square, London WC1N 3BG, UK A retrospective study was performed in 32 patients with