With great patience and moderate pressure one can succeed in artificially injecting the lymphatics without causing extravasation. It may even be the case that only one, or at most one or two ampullæ are affected. Microscopically the ampullæ and trabeculæ are found more or less filled with brown bodies or globi. These are evidently lymph cells which have become filled with bacilli and their degenerative products—granules.
One could hardly have a better demonstration of the functions of the lymphatic glands, as filters, than in these leprous glands. The circulation through them is not arrested; nevertheless, the glands retain the infectious product, and if it pass one gland it is arrested and retained in the next. Sometimes the quantity of this infection is so small that one or two ampullæ are sufficient to retain the whole of it. This indicates that the circulation in the gland does not take place exclusively through the lymph sinuses, but that the lymph reaching the gland must at once enter the ampullæ. A similar process is seen in tubercular lymphatic glands, in which one often finds only one or one or two ampullæ infiltrated with tubercle.
In the nerves the bacilli are found partly in round cells, which lie around the vessels and between the nerve fibres, and partly in the cells of Schwann’s sheath; here also they break down into granules, and in time completely disappear. The finer details of the affection of the nerves are best studied on the ciliary nerves when the eye is affected, because there one can examine the finest nerves without cutting sections or putting them through any manipulation which might injure them. One often sees the myelin sheath pressed in by bacilli or cells filled with granules ([Plate XII], Fig. 2), and one finds nerve fibres without a myelin sheath and with a more or less atrophic axial cylinder ([Plate XII], Fig. 1). These drawings clearly explain how the pressure on the axial cylinder at first causes pain, and later, when atrophy has set in, anæsthesia. And one can also understand that when the leprous affection passes off without complications, the axial cylinders are again restored and become functionally active.
But on those places above referred to, where the nerves run superficially over bones or joints, and are exposed to pressure and stretching, secondary inflammation is added to the process.
While the primary leprous affection hardly appreciably thickens the nerves, the secondary inflammation causes a very marked thickening. The ulnar nerve at the elbow may attain a diameter of 7 to 8 mm. or more, and when the secondary inflammation disappears the connective tissue contracts, and the previously thickened nerve becomes thinner than normal. This whole process usually advances very deliberately, and years are required before anæsthesia is developed to its full extent. While the section of the thickened nerve is quite smooth and of a pale brown colour from the numerous globi present, the section of the atrophic nerve, though also smooth, is as pale as the section of a tendon. It consists almost exclusively of connective tissue; every trace of bacilli has disappeared, and one sees hardly a suggestion of nerve fibres. The leprous affection is healed, but only a completely functionless rudiment of the nerve remains.[4]
Chapter IV.
LEPRA MACULO-ANÆSTHETICA.
This form of leprosy was first distinctly and well described by Danielssen, who called it L. anæsthetica; but since the macules, as Danielssen recognised, play an important and constant rôle in the course of the disease, we prefer the name maculo-anæsthetica, as it includes the two most striking symptoms; the name L. nervorum used by many investigators, we do not consider satisfactory. Certainly the nerves suffer most, and the neuritis is the most prominent feature in the disease, but the skin affection is a bacillary one, which precedes or accompanies the neuritis; it is not, as is often believed, a tropho-neurosis, as we have determined by the demonstration of bacilli in both young and very old leprous patches.
Thus there disappears the sharp distinction between the two forms of the disease—the tuberous and the maculo-anæsthetic. We must regard them as the same disease, only with varied intensity in the action of the bacilli.
One can distinguish in the maculo-anæsthetic form, different stages in the course of the disease, but in general they cannot be very sharply defined from one another.
In the prodromal stage, which is of very varied duration, lasting for months or even years, the patients state that they suffer from exhaustion, general debility, rheumatoid pains of the joints or muscles, hyperæsthesia of the skin, neuralgic pain of certain nerve regions, sopor and mental depression. Ephemeral eruptions of spots are admitted; and pigmentary anomalies, sometimes atrophic, sometimes hypertrophic, were noted by Bidenkap.