Spinal Analgesia

To obtain spinal analgesia, 1/4 or 1/2 grain (0.015-0.03 gm.) of cocaine hydrochloride in aqueous solution is injected into the spinal canal, the needle being inserted between the third and fourth lumbar vertebrae into the region of the cauda equina. The toes and perineum become anesthetic in about three or four minutes, and the anesthesia rapidly ascends until it reaches about to the umbilicus, the whole of the body below this point being anesthetized. There is little or no muscular relaxation; the sense of touch may not be altogether abolished, and the sensations of heat and cold are unchanged. (See also Shock and Collapse.)

Jonnesco has recently made the injections higher up in the spinal cord, using a mixture of stovaine and strychnine. He reports using the method without a fatality in 1005 patients, ranging from one month to eighty-two years. Transient arrest of respiration occurred seven times. He reports 1958 cases of its use by others with safety. But this method has not met with favor in this country, and after many trials has been abandoned as unsafe. Gray and Parsons and Smith and Porter obtained a pronounced fall in blood-pressure from the high injections and not from the low. Experimentally, it has been shown that cocaine injected into the spinal canal can absolutely block the strychnine convulsions of that region, but the strychnine convulsions come on in the muscles supplied by the uncocainized parts of the cord. Gabbett (1910) reports a death from the injection of novocaine, 1 1/2 grains (0.6 gm.), and strychnine hydrochloride, 1/65 grain (0.001 gm.). The convulsions affected the arms, but not the legs.

The Eye

If a drop of 2 or 4 per cent. aqueous solution of cocaine hydrochloride is dropped into the eye, the immediate effect is marked irritation, with reflex contraction of the pupil. But this is followed quickly by anesthesia of cornea and conjunctiva, with blanching, retraction of the eyelids, and absence of the winking reflex in response to an irritant. A few minutes later the pupil becomes dilated, and remains so for one or two hours. The pupil still reacts to light, though only partially, and there is neither paralysis of accommodation nor decrease in intra-ocular tension, so the effect on the eye is different from that produced by atropine. This is further shown by the fact that in a fully atropinized eye cocaine still further dilates the pupil, and that in a cocainized eye the pupil contracts on electric stimulation of the third nerve, either centrally or distally to the ciliary ganglia. These experiments show that it does not act on the third nerve. The action of the cocaine is evidently a peripheral one. If it is injected into an excised eye, it causes the same dilatation of the pupil. If the superior cervical ganglion (from which the pupil-dilating fibers emanate) is removed from one side of an animal, and after the wound has healed and the nerves have had time to degenerate, cocaine is dropped in each eye, there is a dilatation of the pupil on the intact side, but on the other side only slight dilatation if any. Hence, though there may be some depression of the circular muscles, the main action is stimulation of either the radial muscle-fibers or some part of their (sympathetic) nerve-supply.

Accommodation is not paralyzed, as the ciliary muscle is not affected; so cocaine is not available in fitting glasses.

The intra-ocular tension is not increased, and in spite of the dilatation of the pupil, which lasts only an hour or two, may be diminished. This effect is thought to be due both to the shrinkage of the vessels of the eyeball and to the consequent diminution in secretion.

If one drop of a 4 per cent. cocaine solution is dropped in the eye every minute for five minutes, the pupil will be fairly dilated in about five minutes more, and the dilatation will last for from one to two hours. A danger is the drying of the cornea, with ulceration or clouding.

The Stomach

Cocaine is locally anesthetic, and will prevent vomiting from local irritants. It is of interest that in the Andes Mountains the natives chew coca leaves, and if they have a plentiful supply of coca, can continue to work for several days without food. They seem to have no feeling of hunger so long as food is kept out of their sight, but the appetite returns if they see or smell appetizing food. Probably there is diminished sensation in the stomach and in the mouth, and consequent absence of the effect on appetite of reflexes from these regions, while the psychic elements in the production of appetite (the sight or smell of food) remain intact. The psychic stimulation is also probably a factor in producing increased power to work. It is said that 100,000,000 pounds of the leaves are used annually in South America, the people chewing them with the addition of a little chalk or lime.

These effects have not been obtained in other localities, and consequently have been attributed to some unexplained property which is confined to the fresh or freshly dried coca leaves. But Sollmann thinks that these effects have failed in northern regions because the drug has not been tried in conditions of marked hunger and fatigue. Miiller and also Schlesinger found little or no abolition of hunger by cocaine, though it abolished the feeling of weakness.

Disagreeable central effects upon the alimentary tract which not infrequently follow the absorption of cocaine, as in spinal anesthesia, are nausea, vomiting, and diarrhea. The cause of these is not known.

Systemic Effects

The systemic effects are not made use of in therapeutics, and may be studied rather because of their manifestation in poisoning.