The most common of nervous sequelm is neurasthenia. The neurasthenia fol lowing influenza differs but little from the various recognized types of this affec tion. We meet with the cerebrospinal, the spinal, and the sympathetic type. A noteworthy feature of the cerebrospinal type is the great depression, amounting to melancholia, with suicidal tendencies; so that the term neurasthenia no longer applies to this affection.
The spinal form of neurasthenia is a less common sequel of influenza. In a few cases observed it was accompanied by marked symptoms of hysteria.
In the sympathetic variety we meet with a group of symptoms, sonic relating to the heart, others to the sexual organs. Bradycardia. with a slow pulse of 40 or 50, is often ebserved to occur with influ enza; we meet with an irregular or in termittent pulse accompanied by attacks of syncope; occasionally also attacks of the nature of angina pectoris have been noted following influenza, where there was neither gout nor arteriosclerosis, or any other palpable cause for the attacks. In some cases the myocardium is most likely also affected, which may account for the sudden death occurring after in fluenza.
Among the post-influenzal nervous affections of an organic nature is most important peripheral neuritis. Various forms of peripheral neuritis have been ob served. In a few cases all four extremi ties are affected.
Much more common than the former is a more limited neuritis, affecting some times only one limb or the two limbs on one side. The affection comes on some days or a week after the recovery from the influenza, the patient complaining of more or less severe pain in the limb, some weakness of certain groups of muscles comes on; in the lower extremities the anterior group of muscles of the leg and flexors of the knee are mostly affected; in the upper extremities the scapulo humeral muscles, or sometimes the exten sors of the wrist and fingers become in volved; there is generally, also, dims thesia; the reflexes are first increased, afterward diminished, but rarely become quite absent. Recovery is generally very slow.
A third form resembles diphtheritic pa ralysis. Here there is paresis of accom modation, and in some few cases pharyn geal and laryngeal paralysis, and it is perhaps a nuclear affection rather than a peripheral neuritis. J. Dreschfeld (Med.
Chron., Mar., '98).
Meningitis and pseudomeningitis may occur as the direct or indirect result of influenza. In attempting to differentiate an influenza] meningitis from other forms useful criteria may be found: (1) in Shelley's sign (the presence of a sago like looking eruption on the palate and lips); (2) in the influenzal tongue,—a peculiar opaline, bluish-white, porcelain like appearance, which resists purgative treatment, and lasts throughout the dis ease; (3) in the study of the tempera ture, which presents irregular rises, each rise a little less than the preceding, and with marked oscillations between the morning and evening temperatures; (4) in lumbar puncture. Sassi (GFIncura bili, An. 14, F. 17 and 18, '99).
Attention drawn to the importance of obtaining a history of recent influenza before the administration of anaesthetics, especially of chloroform; there have been large numbers of deaths from chloroform administration, and this is especially the case during influenza epidemics. Very suspicious cases have occurred, which were clearly explained by the depressed condition of the nervous system and of the heart. William Calwell (Brit. Med. Jour., Sept. 29, 1900).
Surgical complications of influenza. Its toxic action is noted in the central and peripheral nervous system and the general condition. Its inflammatory ef fects are found upon all mucous mem branes. Influenza bacilli enter the organism by all routes, reach the blood, and then become wide-spread. G. Perez (Deutsche Zeit. f. Chir., Nov., 1902).
While the foregoing history and symp toms of influenza relate to its true epi demic prevalence, it is proper to state that sporadic cases, presenting all the more characteristic symptoms, are met with during every winter in the temper ate zone, particularly during the first two or three days of high temperature following a week of intense cold.
Diagnosis.—The coincident develop ment, without premonition, of general febrile symptoms, violent pains in the head, back, limbs, and various parts of the chest or abdomen, catarrhal irrita tion of the membranes of the respiratory passages or alimentary canal, or both, with mental and nervous depression, is so characteristic of this disease as to render the diagnosis easy.