Jules Joseph Dejerine (1849–1917) did numerous publications in all fields of neurology including on cerebellar pathology thanks to his successful collaboration with André-Thomas (1867–1963) (Figure 1), one of his most skilled pupils. André-Thomas made his entire medical career in Paris [1Anonymous André Thomas (1867–1963) Rev Neurol (Paris) 1963 ;  109 : 5-12

Cliquez ici pour aller à la section Références]. He was appointed intern in 1892, and spent three years with his mentor Dejerine, first at Bicêtre, and then at Salpêtrière hospitals. André-Thomas pursued after 1911 his clinical work at Saint Joseph Hospital. In parallel, he was chief of Dejerine laboratory at the Salpêtrière until the death of his master in 1917. André-Thomas’ most important research focused on the cerebellum.

This essay brings to mind the advances in the delineation of the cerebellar syndrome at the turn of the 19th and 20th centuries with special accent on André-Thomas own contribution. It also emphasizes the seminal description by Dejerine and André-Thomas in 1900 of olivo-ponto-cerebellar atrophy (OPCA) [2Dejerine J., Thomas A. L’atrophie olivo-ponto-cérébelleuse Nouvelle Iconographie de la Salpêtrière 1900 ;  13 : 330-370

Cliquez ici pour aller à la section Références] and the evolution of ideas on this new syndrome during the 20th century.

On an historical point of view [3Thomas A. Le cervelet, étude anatomique, clinique et physiologique  Paris: G. Steinheil (1897). 

Cliquez ici pour aller à la section Références], the first investigations on the functions of the cerebellum were made during the 19th century by lesion experiments in animals notably in birds and dogs. Particular contribution should be credited in Paris to Marie-Jean-Pierre Flourens (1794–1867) who revealed in 1824 the role of the cerebellum in the coordination of movements and in Florence, Italy, to Luigi Luciani (1840–1919) who described in 1891 the triade asthenia, atonia and astasia. These signs were later considered as, respectively, impaired strength, hypotonia and ataxia. Undoubtedly, André-Thomas was inspired by the work of these researchers and encouraged by his mentor Dejerine to investigate the cerebellar dysfunction both with experiments in animals and clinical pathological studies in humans. His medical thesis on the cerebellum in 1897 is a masterpiece of 370 pages [3Thomas A. Le cervelet, étude anatomique, clinique et physiologique  Paris: G. Steinheil (1897). 

Cliquez ici pour aller à la section Références]. During the following decades, André-Thomas did several original reports and books on cerebellar dysfunction.

The clinical description of the cerebellar syndrome took place between 1890 and 1920. Among many authors, Joseph Babinski (1857–1932) and André-Thomas in Paris and Gordon Holmes (1876–1966) at Queen Square in London were the most important contributors [4Garcin R. The ataxias Amsterdam: North Holland (1969).  309-355

Cliquez ici pour aller à la section Références]. Each of these authors explored all components of cerebellar ataxia including tremor and made original contributions or special interpretations. Indeed, Babinski reported asynergia, he differentiated from ataxia (dissociation of movements of different body segments which are associated in a single act, as when passing from a recumbent to a sitting position or during initiation of gait), hypermetria and adiadochokinesia (impairment in performing rapid successions of alternating movements such as pronation and supination of the hand). André-Thomas added dysmetria, dyschronometria (studied in cases with unilateral cerebellar lesions) and passivité with the pendular reflex (considered for a long time by him as resulting from a diminished myotatic reflex before accepting its link to hypotonia). Gordon Holmes definitely anchored the concept of hypotonia with the rebound phenomenon (Stewart-Holmes maneuver), resulting from a delayed response to stretching of antagonist muscle. He also described delayed initiation or arrest of movement, explored action tremor and identified rubral or thalamic tremor (today Holmes tremor). In conclusion, it is important to recall the contribution of André-Thomas to the study of the cerebellum, since, although cited by Gordon Holmes in his Croonian Lectures in 1922 [5Holmes G. Clinical symptoms of cerebellar disease and their interpretation. Croonian Lectures Lancet 1922 ;  202 : 142-147[148–53].

Cliquez ici pour aller à la section Références], it is often ignored in master books in contrary to that of Joseph Babinski and especially Gordon Holmes.

In 1900 Dejerine and André-Thomas described a new syndrome they named olivo-ponto-cerebellar atrophy (OPCA) about two patients including one autopsied case [2Dejerine J., Thomas A. L’atrophie olivo-ponto-cérébelleuse Nouvelle Iconographie de la Salpêtrière 1900 ;  13 : 330-370

Cliquez ici pour aller à la section Références]. This degenerative disease occurred at middle or elderly age. The first signs were staggering gait and the disease course was of several years. The main pathological features were a severe atrophy of the cerebellum with loss of Purkinje cells, and of inferior olives, middle cerebellar peduncles and pons. Dejerine and André-Thomas considered that their cases were different from Friedreich’ ataxia and from Pierre Marie's cerebellar heredoataxia, but also from the familial Menkes form of OPCA since the disease was sporadic and the dorsal columns of the spinal cord were spared. Neither the Locus niger (substantia nigra) nor the basal ganglia were examined in the autopsied case. Subsequently, other clinical pathological case reports of OPCA were made and additional signs were depicted, notably extrapyramidal symptoms.

In 1948, Critchley and Greenfield definitely recognized sporadic OPCA as a specific entity [6Critchley M., Greenfield J.G. Olivo-ponto-cerebellar atrophy Brain 1948 ;  71 : 343-364

Cliquez ici pour aller à la section Références]. In an international conference on OPCA during the 1980s, a classification of several variants of familial and sporadic OPCA was suggested [7Duvoisin R.C., Plaitakis A. The olivopontocerebellar atrophies. Advances in Neurology, Vol. 41  New York: Raven Press (1984). 

Cliquez ici pour aller à la section Références]. Meanwhile, as it is well known, two other sporadic degenerative syndromes with sometimes overlapping features with OPCA had been described in the 1960s, the Shy-Drager syndrome (with prominent orthostatic hypotension) and Adams-Van Bogaert striatonigral degeneration (with severe parkinsonian signs and degeneration of the caudate and putamen). An overlapping of the clinical and pathological features between the two syndromes and OPCA was thereafter noted. In the late 1980s, new histopathological data showed that these entities shared common oligodendroglial inclusions with different anatomical distributions. Therefore, the three syndromes were later coalesced under the term multiple system atrophy (MSA) [8Quinn N.P. Multiple system atrophy. The nature of the beast J Neurol Neurosurg Psychiatry 1989 ;  32 : 78-89 [cross-ref]

Cliquez ici pour aller à la section Références].

The concept of MSA is nowadays adopted internationally, with two main features, MSAp with prominent parkinsonian syndrome, and MSAc (i.e. sporadic OPCA) with mostly a cerebellar syndrome and inconstant involvement of the substantia nigra and of the caudate and putamen. Today, patients with sporadic OPCA are still identified in clinical practice with helpful MRI signs showing cerebellar and pons atrophy reminiscent of the first anatomical case described by Dejerine and André-Thomas in 1900 (Figure 1).