Studies on the sympathetic nervous system in tetanus

Tetanus: pathophysiology, management, and prophylaxis

As tetanus has become a rare disease in the developed world, physicians have become less comfortable with its diagnosis and management. The extent of adequate antitetanus immunity in the adult population, especially the elderly, is waning, in great measure because primary care physicians have not made prophylaxis a priority in their routine encounters with patients. Furthermore, as the population of immunocompromised hosts grows, an increasing percentage of our patients may not respond to standard active immunization routines. Unless these trends are reversed, we face a substantial increase in the incidence of this dread disorder. Tetanus is also of interest as a relatively simple model of disordered motor control that can instruct us in the management of the many more common causes of neurogenic muscular rigidity. The toxin produced by Clostridium tetani finds increasing use in laboratories investigating brain function as well. Clinical tetanus is divided into four symptomatic types: generalized tetanus, local tetanus, cephalic tetanus, and neonatal tetanus. This monograph discusses the diagnostic aspects of each type of tetanus, its pathophysiology, diagnosis, differential diagnosis, and treatment. Preventing tetanus should be a high priority for all primary care physicians. Active immunization with tetanus toxoid is remarkably effective and safe. Passive immunization with human tetanus immune globulin is indicated in certain circumstances, which are discussed below.

Retrograde, trans-synaptic and transneuronal transport of fragment C of tetanus toxin by sympathetic preganglionic neurons

The atoxic binding fragment of tetanus toxin, Fragment C, was injected into paravertebral ganglion 14, the avian homologue of the mammalian stellate ganglion. Postinjection survival intervals were varied from 2.5 h to 33 days. Experiments performed at the shortest survival time of 2.5 h showed that Fragment C was retrogradely transported by sympathetic preganglionic axons at a rate greater than or equal to 10 mm/h. At survival times ranging from 5 to 15 h. Fragment C-positive, retrogradely labeled sympathetic preganglionic neurons were observed within the last cervical spinal segment and throughout the first three thoracic spinal cord segments. Sporadic retrograde labeling of sympathetic preganglionic neurons was evident within the fourth and fifth thoracic spinal cord segments. Fragment C-labeled perikarya and dendrites exhibited both diffuse cytoplasmic immunostaining as well as intracellular, perinuclear accumulations of small. Fragment C-positive granules. Retrogradely labeled preganglionic neurons were found within both autonomic subnuclei within avian thoracic spinal cord; the column of Terni and the nucleus intercalatus spinalis. The distribution and numerical density of retrogradely labeled sympathetic preganglionic neurons indicated further that: (a) both myelinated and unmyelinated preganglionic axons appear to be capable of intra-axonally transporting Fragment C; and (b) it is unlikely that there is differential Fragment C labeling of a morphologically distinct population of sympathetic preganglionic neurons within or across subnuclei. Fragment C is transferred out of sympathetic preganglionic somas and dendrites into the surrounding neuropil at an aggregate rate greater than or equal to 5 mm/h. Trans-synaptic transport was evident at postinjection survival times as short as 5 h and continued to increase in density within the sympathetic preganglionic neuropil for 24 h. Fragment C-positive terminal labeling persisted for at least 20 days. At survival times greater than or equal to 1 day. Fragment C-positive puncta and weak intracellular labeling of neurons were evident in areas of the spinal gray outside of the nuclear boundaries of the column of Terni and nucleus intercalatus. The regions showing evidence of trans-synaptic and transneuronal labeling included: (a) a group of small cells dorsal to the column of Terni, (b) lamina V and (c) lamina VII. This expansion of Fragment C-labeled neuronal elements was segmental in organization and co-extensive with the retrograde labeling pattern of sympathetic preganglionic neurons. Spinal interneurons in these regions may provide segmental, monosynaptic input to sympathetic preganglionic neurons. Fragment C leaked into the systemic circulation from the site of injection in paravertebral ganglion 14.(ABSTRACT TRUNCATED AT 400 WORDS)

Selective uptake of C-fragment of tetanus toxin by sympathetic preganglionic nerve terminals

Immunohistochemical techniques have shown that the C-fragment of tetanus toxin injected into medial gastrocnemius muscle in the guinea-pig and rat, in addition to its retrograde transport in the axons of the somatomotor, sympathetic and sensory neurons supplying this muscle, is taken up and concentrated by terminal varicosities within pre- and paravertebral sympathetic ganglia at all thoracolumbar levels. Staining was absent in chronically denervated ganglia, demonstrating the specific association of the antigen with preganglionic varicosities. Preganglionic varicosities at all levels were also labelled after C-fragment injection into the peritoneal cavity or into denervated medial gastrocnemius; both of these procedures failed to label somatomotor or sensory neurons. Although retrograde trans-synaptic transport could be demonstrated, sympathetic labelling was sparse and non-specific, so that the C-fragment of tetanus toxin is unsuitable for the identification of sympathetic pathways. The selective and widespread uptake of tetanus toxin by sympathetic preganglionic terminals could explain the diverse autonomic symptoms observed in tetanus intoxication.

Dysfunction of the sympathetic nervous system in tetanus. A study of 3 cases

In severe cases of tetanus an overactivity of the sympathetic nervous system has been postulated because of the clinical symptoms including hypertension, fluctuating blood pressure, tachycardia, tachyarrhythmia and peripheral vasoconstriction. In the present study the involvement of the sympathetic nervous system in tetanus was investigated by serial determinations of plasma adrenaline (A) and noradrenaline (NA) in 2 patients who developed severe symptoms of tetanus and the characteristic cardiovascular disturbances. Sustained high circulating levels of NA and A could be observed indicating a prolonged overactivity of the sympathetic nervous system. In one case, the elevation of the NA level in plasma persisted until the disturbances of the motor nervous system ceased. In a third case of tetanus without cardiovascular abnormalities, the plasma NA and A only increased slightly on a few occasions. The results demonstrate that an overactivity of the sympathetic nervous system can complicate the course of severe tetanus.

Haemodynamic changes during experimental tetanus toxicity in dogs

Haemodynamic variables were compared in control dogs, dogs with local tetanus toxicity and dogs with generalised tetanus toxicity. The results showed an increase in the inotropic and chronotropic activation of the heart in both groups of tetanus dogs, but there was no significant change in the mean systemic blood pressure and the common carotid occlusion reflex was unchanged. Spontaneous fluctuations in the systemic blood pressure were observed in some dogs with tetanus, and occurred more often in those with generalised tetanus. The modification of these fluctuations by beta-adrenergic blockade and diazepam, suggest that they are of autonomic neural origin. It is suggested that these changes in the cardiovascular system are the results of neurophysiological and biochemical changes in the sympathetic nervous system, which have been reported to occur in tetanus.

Effect of tetanolysin on platelets and lysosomes

Tetanolysin, partially purified, caused the lysis of human and rabbit platelets, as determined by a decrease in the optical density of platelet suspensions and the release of serotonin, enzymes, and protein. This lytic activity was neutralized by antitoxin. In addition, a suspension of the lysosome-containing large granule fraction of rabbit liver released hydrolytic enzymes when exposed to tetanolysin. Thus, tetanolysin can be added to the list of bacterial toxins that are lytic for a variety of cellular or subcellular membranes. These findings provide additional data that suggest that tetanolysin may contribute to the pathogenesis of some of the unusual manifestations observed in clinical tetanus.