Regional cerebral blood flow and CSF pressures during the Cushing response induced by an infratentorial expanding mass

An experimental study was carried out in eight dogs to investigate whether the Cushing response (CR) during intracranial hypertension is due to pressure per se, tissue distortion, or ischemia in the brain stem. To minimize the effects of rostrocaudal displacement, intracranial pressure was raised by an expanding mass lesion located in the posterior fossa. Regional cerebral blood flow (rCBF) was measured with radioactive microspheres and compartmental cerebrospinal fluid (CSF) pressures were recorded during the CR which was induced by the continuous inflation at a constant rate of an infratentorial epidural rubber balloon in two groups of four dogs. In one group (A) rCBF was measured at the onset of the CR and in the other group (B) at the peak of the systemic blood pressure rise. In the animals of group A blood flow in the mesencephalon, pons and upper medulla oblongata was reduced from control values by 32%, 57% and 85% respectively. In group B blood flow in the same areas did not differ significantly from pre-inflation values. In contrast, the recorded balloon volume, which was assumed to be an index of mechanical distortion of the brain stem, varied considerably at the beginning of the blood pressure rise (from 2.5 to 4.7% of the calculated intracranial space). Similarly, CSF pressure in the posterior fossa at the onset of the CR also varied considerably (from 52 to 117 mmHg). Thus, the large quantitative variations meant that both absolute pressure and tissue distortion were poor predictors of the onset of the CR. The findings suggest that ischemia, rather than brain stem distortion per se or pressure by itself, is responsible for the initiation of the CR. The rise in blood pressure elicited during the CR seems capable of restoring blood flow in the brain stem back to control values.

Regional cerebral blood flow and CSF pressures during Cushing response induced by a supratentorial expanding mass

In order to delineate the critical blood flow pattern during the Cushing response in intracranial hypertension, regional cerebral blood flow was measured with radioactive microspheres in 12 anesthetized dogs at respiratory arrest caused either by expansion of an epidural supratentorial balloon or by cisternal infusion. Regional cerebrospinal fluid pressures were recorded and the local cerebral perfusion pressure calculated in various cerebrospinal compartments. In the 8 dogs of the balloon expansion group, the systemic arterial pressure was unmanipulated in 4, while it was kept at a constant low level (48 and 70 mm Hg) in 2 dogs and, in another 2 dogs, at a constant high level (150 and 160 mm Hg) induced by infusion of Aramine. At respiratory arrest, regional cerebral blood flow had a stereotyped pattern and was largely independent of the blood pressure level. In contrast, concomitant pressure gradients between the various cerebrospinal compartments varied markedly in the 3 animal groups, increasing with higher arterial pressure. Flow decreased by 85-100% supratentorially and by 70-100% in the upper brain stem down to the level of the upper pons, while changes in the lower brain stem were minor, on the average 25%. When intracranial pressure was raised by cisternal infusion in 4 dogs, the supratentorial blood flow pattern at respiratory arrest was approximately similar to the flow pattern in the balloon inflation group. However, blood flow decreased markedly (74-85%) also in the lower brain stem. The results constitute another argument in favour of the Cushing response in supratentorial expansion being caused by ischemia in the brain stem. The critical ischemic region seems to be located rostrally to the oblongate medulla, probably in the pons.

Influence of blood pressure on tolerance to an intracranial expanding mass

In 3 groups of 4 dogs with normotensive, induced-hypotensive and induced-hypertensive blood pressure respectively, continuous expansion of an extradural supratentorial balloon led to respiratory arrest at inflation volumes which increased with increasing blood pressure. This positive correlation between the volume tolerance to an expanding lesion and blood pressure was also found in similar experiments on 4 hypotensive and 4 hypertensive cats. Monitoring cerebrospinal fluid pressures in the cerebral lateral ventricles, in the posterior fossa and in the spinal subarachnoid space showed that absolute pressures in the various compartments as well as the intercompartmental pressure gradients at the moment of respiratory arrest were increased in proportion to the level of the systemic arterial pressure in each case. These observations do not support current concepts that brain-stem distortion alone or that stimulation of baroreceptors in the posterior fossa are responsible for eliciting the Cushing response. The fact that the supratentorial perfusion pressure was the only parameter which did not differ significantly under the different experimental conditions suggests that the mechanism responsible for the respiratory arrest is local brain tissue ischemia, probably near the tentorial incisure. The magnitude of gain in volume tolerance, when mean arterial pressure was varied from 60 mmHg to 190 mmHg, was 87% suggesting that the blood pressure may have a critical role in an intracranial lesion. These findings have clinical implications.

Changes of pituitary hormones in brain death

In six patients with clinical and electroencephalographic signs of brain death, pituitary hormones such as prolactin, human growth hormone (GH), luteinizing hormone (LH), and thyrotrophin (TSH) were measured in blood close to the demonstration of intracranial circulatory arrest by angiography. In addition, pituitary hormone releasing tests and an insulin test were carried out in two patients. The results showed that no patient had a general decrease in hormone levels, according to their biological half life times, which suggests there still was some function in the hypothalamus and pituitary. This was supported by the results of the stimulation tests. It is concluded that in brain death some basal parts of the brain may still be perfused despite the fact that angiography indicates circulatory arrest in these areas.

Laminated Diatomaceous Sediments from the Guaymas Basin Slope (Central Gulf of California): 250,000-Year Climate Record

During Deep Sea Drilling Project-International Program of Ocean Drilling leg 64, December 1978 to January 1979, the initial test of the Deep Sea Drilling Project's hydraulic piston corer obtained an almost undisturbed section from a 152-meter hole into the sediments of the oxygen minimum zone at a depth of 655 meters along the Guaymas slope in the central Gulf of California. The section records variations in climate, productivity, and circulation for more than 250,000 years of Late Pleistocene to Holocene history with recordings of seasonal variations in these parameters in the laminated sections.

Multiple sclerosis and narcolepsy/cataplexy in a monozygotic twin

Symptoms of narcolepsy/cataplexy developed in a monozygotic twin at the age of 56 years, 25 years after the onset of multiple sclerosis. The diagnosis of narcolepsy/cataplexy was confirmed by polygraphic recordings demonstrating sleep-onset periods of rapid eye movements (REM), increase in REM time per 24 hours, and disturbed nocturnal sleep. Frequent catapletic attacks were almost completely controlled by clomipramine. These symptoms may constitute one of the paroxysmal syndromes in multiple sclerosis. The discordancy for multiple sclerosis is attributed to a submaximal risk factor in the HLA system and a strong environmental factor in only one of the twins.

The cerebral lesions in a patient with generalized glutathione deficiency and pyroglutamic aciduria (5-oxoprolinuria)

The clinical and pathologic features of a male patient with generalized glutathione deficiency and pyroglutamic aciduria are presented. The patient died at the age of 28 years. He was mentally retarded from infancy and developed progressive tremor, retardation of movement, and ataxia as from the age of 16. Neuropathologic examination of the brain disclosed a selective atrophy of the granule cell layer of the cerebellum and focal lesions in the visual cortex and the thalamus. The type and distribution of the lesions resembled those seen after mercury intoxication. However, in our patient the damage was probably caused by the lack of protection of glutathione against oxidative damage in the brain. Possible treatment of this rare metabolic disorder might include external supply of an antioxidant, e.g., a thiol capable of penetrating the blood brain barrier.

[Demonstration total brain infarct with radioisotope angiography]

In the field of organ transplantation and in brain death patients where intensive-care measures may seem superfluous, the demonstration of cessation of cerebral blood flow by X-ray angiography is generally agreed to be the diagnostic procedure of choice to prove irreversible loss of cerebral function. There are, however, certain drawbacks involved in X-ray angiography. Arterial puncture is necessary. Furthermore, the procedure can be time-consuming, thus making the continuation of adequate intensive-care measures more difficult. At the same time the circulatory condition may worsen causing hypoxic damage to the organ to be transplanted. In the present paper, the authors report on 13 patients with clinical signs of brain death where cessation of cerebral blood flow was demonstrated atraumatically by intravenous radioisotope angiography (RIA) using a multicrystal gammacamera (Baird Atomic) and the bolus-injection technique with 99m Tc-pertechnetate. Nine patients had severe brain injuries, 2 patients had brain tumours, 1 patient had encephalitis and 1 patient had suffered prepartal thrombosis of the sinus sagittalis. In all patients EEG recordings were isoelectric. At the time when the RIA was performed systolic blood pressure had decreased to 62-85 mmHg (x = 71 mmHg), while body temperature had declined to 31-36,5 degrees C (x = 34 degrees). According to the present results, which were all confirmed by subsequent bilateral carotid X-ray angiography, total brain infarction is unequivocal when the following criteria are satisfied using RIA: 1. when the radioisotope bolus flows along the common carotid arteries but does not proceed any further than to the base of the skull or around the scalp structures, 2. when, at the moment when the radioactivity outlines the scalp structures, neither the intracranial arteries nor the capillary bed or the venous sinuses are visible, 3. when the time-activity curves across the hemispheres show simply a plateau of low count rate without the activity peak typical for cerebral tracer circulation and 4. when the activity peak, typical for venous outflow, is missing from the time-activity curves for the cervical areas. In 12 patients with extremely reduced cerebral blood flow it was demonstrated that the RIA findings were clearly different from those obtained at brain death. Moreover, not one of 438 other patients undergoing RIA exhibited the same features which were associated with brain death. The authors conclude that RIA involves the same degree of safety as X-ray angiography in the diagnosis of total brain infarction but is superior to the latter when the diagnostic procedure has to be performed quickly, thus reducing the risk of any further damage to a prospective donor organ.

Nachweis des totalen Hirninfarktes mit der Radio-Isotopen-Angiographie

Bei 13 Patienten mit totalem Hirninfarkt konnte der zerebrale Kreislaufstillstand atraumatisch mit der Radio-Isotopen-Angiographie (RIA) unter Verwendung von 99mTechnetium-Pertechnetat und der Multi-kristall-Kamera innerhalb von 3—4 Minuten sicher nachgewiesen werden.

Aufgrund der bisherigen Befunde, die ausnahmslos mit der angeschlossenen bilateralen Karotiskontrast-angiographie, in drei Fällen auch mit der 133Xe-Gamma-Clearance-Methode bestätigt werden konnten, sind wir der Auffassung, daß die RIA der konventionellen Röntgen-Kontrast-Angiographie bezüglich der Hirntodesdiagnose zumindest gleichwertig, hinsichtlich eines zu sichernden Transplantationserfolges aber überlegen ist, da die schonend und schnell durchzuführende RIA zu keiner weiteren ischämischen Schädigung des zu transplantierenden Organes führt.

Bei weiteren 12 Patienten mit erheblich reduzierter zerebraler Durchblutung (schweres Schädel-Hirn-Trauma, apallisches Syndrom) wurde demonstriert, daß auch diese Zustände von der RIA erfaßt und von dem des totalen Hirninfarktes eindeutig unterschieden werden können.

[A case of Guillain-Barré syndrome following cholera vaccination (author's transl)]

A 45-year-old woman developed bilateral ascending flaccid paralysis after cholera vaccination, 15 days after the first and 1 day after the second injection. The clinical course resulted in nearly complete paralysis of the lower limbs, paresis of the upper limbs and partial involvement of the cranial nerves. There was only slight sensory loss. The CSF revealed no pleocytosis and a protein level of 206 mg/100 ml. Recovery began 2 weeks later and was almost complete after 2 months. Immunological investigations revealed no remarkable changes.