110 Archives de Névrologie, vii. p. 44.
The Family Form of Tabes Dorsalis.
SYNONYMS.—Friedreich's disease, the Family form of locomotor ataxia, Hereditary ataxia, Hereditary tabes.
Friedreich discovered a peculiar form of co-ordinating disturbance in a number of children of the same family, which he brought into relation with a lesion of the posterior columns, and which has been since found by him and by subsequent observers to occur in other cases, always affecting several members of the same family, as in the first case observed by him. The clinical and pathological features, though resembling those of the tabes dorsalis of adults in many respects, are distinct in others, and for this reason it is generally assigned a separate place in classification.
ETIOLOGY.—The disorder is usually manifested in juvenile life, the age of the affected subjects varying from the seventh to the twenty-fifth year. The male sex preponderates in the statistics of the affection. Some neuropathic vice can always be found in the patient's immediate ancestry, and the limitation of the disease to families burdened by such a diathesis is exemplified in the fact that the ninety individual cases thus far accurately studied occurred in thirty-six families.111 The disease type of the ancestors of the patients is usually different from that of the latter. Alcoholism in the father is one of the commonest forms, but convulsions, hysteria, and insanity are also frequent features of the family history. In a few cases tabes dorsalis, properly so called, was present in the father. In others there was consanguinity of the father and mother. In Musso's group the parents had been brother and sister, and their mother had been a melancholic dement. Three other grandchildren and six grandchildren by the incestuous marriage developed the family form of tabes. In this family the frequent experience of hereditary transmission was verified—that the neurotic taint skipped the intermediate generations.
111 Raffaele Vizzioli, Giornale di Neuropatologia, 1885.
CLINICAL HISTORY.—Usually the first symptom is ataxia of the lower extremities; occasionally this is preceded by severe frontal headache or by vague rheumatoid pains. The inco-ordination is very similar to that of true tabes dorsalis, but swaying on closing the eyes is not noticed early in the disease, as in the latter affection. The arms soon become involved in the ataxia, but cutaneous sensibility and the muscular sense remain either intact or nearly so—a fact utilized with some success by Erb in polemicizing against the theory of Leyden that the ataxia of tabes is due to imperfect sensation. Later in the disease, usually after a few years, a peculiar speech-disturbance is noticed, which resembles the scanning of disseminated sclerosis. It depends on ataxia of the tongue and lips. This is usually associated with nystagmus. About this time the patient develops a different set of motor symptoms from those characterizing the onset of the disease; contractures, paralysis, and atrophy are found in the affected extremities; sometimes the patients cannot ascend a stair, owing to their inability to lift the feet high enough. Pes equino-varus, deformity of other joints and of the vertebral column, have been observed112 to result from the associated effects of paralysis and contracture. At this stage some sensory disturbance may be developed, formication having been observed toward the close of the history in a number of cases. But the distribution of this disturbance is usually different from that of tabes dorsalis, being more intense in the trunk than in the extremities or evenly marked in the entire periphery.
112 H. E. Smith, Boston Medical and Surgical Journal, 1885, vol. cxiii. p. 361.
COURSE AND PROGNOSIS.—The progress of this disease is slow. It has not yet been known to be arrested by any therapeutical procedure. Death rarely occurs directly from the disease by exhaustion; more commonly life is cut short by some intercurrent affection. Unless this occurs the patients may survive the commencement of the illness from eight to forty and more years.
MORBID ANATOMY.—The sclerosis which is found to be the constant lesion underlying this disease corresponds in every character to a combined sclerosis of the pyramid tracts and the posterior columns. Usually, the crossed-pyramid tract is degenerated in its spinal course, and the uncrossed in the cervical and dorsal part, which, in many subjects at least, is its whole extent. The cerebral part of the pyramid tract is not affected. The nerve-fibres found normally in the gray substance are materially reduced, probably in dependence upon the atrophy of the great nerve-tracts.