The lateral respiratory neurones of the medulla: their associations with nucleus ambiguus, nucleus retroambigualis, the spinal accessory nucleus and the spinal cord

The clinical picture of rabies in man

After an incubation period of one to two months rabies presents with non-specific prodromal symptoms and often with paraesthesiae of the bitten area. As in canine rabies there are furious and dumb forms of the disease. In man, furious rabies is characterised by hydrophobia: terror and excitation with spasms of inspiratory muscles, larynx and pharynx precipitated by attempts to drink and by a variety of other stimuli. Hydrophobia may represent an exaggerated respiratory tract irritant reflex with associated arousal potentiated by the selective destruction of brain stem inhibitory systmes. Also typical of furious rabies are intermittent episodes of excitement, hallucinations and maniacal behaviour. Focal neurological abnormalities are surprisingly uncommon. Other signs include hypersalivation, tachycardia and hyperpyrexia. Paralysis and coma supervene after a few days: survival rarely exceeds seven days. Dumb or paralytic rabies is an ascending flaccid paralysis with sphincter involvement and sensory disturbances. Death from respiratory and bulbar paralysis occurs after a longer illness than furious rabies. In a minority of cases hydrophobia develops before the terminal coma. Complications include respiratory arrest, pneumonitis, cardiac arrhythmias and interstitial myocarditis, posterior pituitary disorders, and gastrointestinal bleeding. Differential diagnoses of furious rabies include hysterical pseudo hydrophobia, tetanus, other encephalitides, delirium tremens and various other intoxications. Paralytic rabies may have to be distinguished from postvaccinal encephalomyelitis, poliomyelitis and other causes of Landry-type ascending paralysis. Intensive care has produced some promising results: life-threatening complications can be prevented but there is some evidence that the severity of the encephalitis is the ultimate barrier to survival.

Anoxic encephalopathy with predominant involvement of basal ganglia, brain stem and spinal cord in the perinatal period. Report on seven newborns

This study reports subcortical lesions in 7 newborn babies after transient circulatory arrest and/or asphyxia. Basal ganglia, diencephalon, tegmentum of the brain stem and spinal grey matter exhibited extensive necroses in a columnar pattern. The lesions of the telencephalic and cerebellar cortex are less prominent. The spinal cord, available in 3 children, revealed subtotal neuronal loss in all segments. The lesions represent the extreme anoxic damage of the CNS in the perinatal period, comparable with brain death in the adulthood. Moreover, the pattern with predominating subcortical lesions indicates that anoxia affects the grey matter in all levels of the CNS.

Medullary relay neurons in the carotid-body chemoreceptor pathway of cats

Central terminations of the carotid body chemoreceptor afferents were localized by recording field potentials and unit activity evoked by electrical stimulation of the carotid sinus nerve, and unit activity during chemical stimulation of the chemoreceptors. Areas where evoked responses with short latency could be recorded and which contained neurons that responded to carotid body excitation were located in two regions of the medulla, about the level of the obex: a dorsal region which included the nucleus tractus solitarius and the reticular formation just below this nucleus; and a ventrolateral region which included the nucleus ambiguus and the ventrolateral reticular formation around that nucleus. The evoked field responses in the two regions were similar. In these two regions, the only neurons which increased their firing both to NaCN and a decreased PIO2 had a respiratory, bursting activity which was phase locked with phrenic nerve firing. The authors' findings suggest that there is a direct synaptic input from carotid body chemoreceptor afferents onto medullary respiratory neurons.