This experiment investigates the holding property of polyglycolic acid suture in repair of divided dog sciatic nerves and the influence of absorption of this synthetic material on regeneration. The conclusion is that PGA maintains its tensile strength sufficiently long to allow both physical union and good regeneration of the divided nerve. The suture absorption does not influence regeneration.

The relationships between the center and the surround of the receptive field of the rabbit retinal ganglion cell were investigated. This was done by coupling localized light spots and electrical activation of the retina and by analyzing the time of the excitatory and inhibitory periods. The responsiveness to the electrical transretinal pulse revealed a) that ON stimulation in OFF-center cells and OFF stimulation in ON-center cells, elicited a primary period of inhibition with a short latency; b) the long latency response of surround stimulation was not preceded by an inhibitory period unless the center was simultaneously stimulated in the same direction; c) a transient response to a stationary spot of light is followed by a period of inhibition. These results are discussed in relation to the known cellular retinal networks.

The general outline of the complete prospective study of 50 cases of spino-cerebellar degeneration is given. The general protocol followed, the criteria for inclusion and the mode of analysis are described. The aim of this study was to establish a base of clinical, physiological and biochemical facts upon which a logical and systematic approach to pathogenesis and treatment of Friedreich's ataxia could be attempted.

A short outline is given of the pioneer efforts of Nicolaus Friedreich in the description of the spinocerebellar degeneration which now bears his name.

The 50 patients in this survey were classified by a panel of neurologists into 4 clinical sub-groups: Group la (“typical” Friedreich's ataxia, complete picture), Group lb (“typical” Friedreich's ataxia, incomplete picture), Group Ila (“atypical” Friedreich's ataxia, possible recessive Roussy-Levy syndrome), Group lib (heterogeneous ataxias). The clinical symptoms and signs were analyzed for each of these groups. A constellation of signs constantly present in Friedreich's ataxia and obligatory for diagnosis was described. Other important symptoms, such as the Babinski sign, kyphoscoliosis and pes cavus were found to be progressive, but not essential for the diagnosis at any given time. Finally, a host of other symptoms can only be called accessory. The progression of scoliosis was found to be an important tool in the differential diagnosis of ataxias. Our study also indicates, in contrast to the opinion of some authors, that absent deep tendon reflexes in the lower limbs and early dysarthria are essential in “typical” Friedreich's ataxia.

This study consists of two parts: I. A detailed genetic analysis of 35 sibships in which 58 individuals were affected with Friedreich’s ataxia; and 2. Clinical and laboratory examinations of parents and siblings, in an attempt at carrier detection and diagnosis of the pre-clinical state.

The increased parental consanguinity, the lack of affected individuals in other generations, and the lack of significance of extrinsic etiological variables, all suggested an autosomal recessive mode of inheritance, and this was confirmed by formal genetic analyses, employing several different methods.

Associated abnormalities in our series of 58 patients included cardiomyopathy (51.7%), diabetes melitus (19.0%), optic atrophy (5.2%), nerve deafness (5.2%) and congenital malformations (6.9%). The incidence of diabetes mellitus. congenital malformations, and epilepsy and lor febrile convulsions was elevated in first degree relatives of patients with Friedreich’s ataxia.

Examinations in first degree relatives revealed an increased frequency of neurological and skeletal abnormalities (26.3%). but no abnormalities on neuro-ophthalmological examination. Frequent EMG abnormalities were noted in parents (56.3%). but not in siblings; and these could usually be attributed to extrinsic causes. There was an increased incidence of ECG abnormalities in both parents (50.0%) and siblings (25.0% and some of these abnormalities may represent cardiomyopathy. An increased frequency of EEG abnormalities was also recorded in parents (14.3%) and siblings (27.2%). but these were not specific. None of these examinations resulted in a practicable method of carrier detection or preclinical diagnosis.

Since carrier detection is still not feasible, genetic counselling remains the only possible means of prevention of Friedreich’s ataxia.

A preliminary genealogical investigation of all the known ancestors from the year 1608 of 4 apparently unrelated French Canadian kindreds with Friedreich’s ataxia reveals that the original ataxia gene in the province of Quebec was present within a core of no more than 10 families living in Quebec City in the mid-1600's.

No chromosomal anomaly was found in 15 cases of typical Friedreich’s ataxia and three cases of atypical recessive ataxia studied with Q and G banding techniques. No difference between frequency of chromosomes gaps or breakages was noted amongst patients with Friedreich’s ataxia and controls.