Compendium of regional diagnosis in affectations of the brain and spinal cord / Translated by F.S. Arnold.

  • Bing, Robert.
Date:
1913
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Licence: In copyright

Credit: Compendium of regional diagnosis in affectations of the brain and spinal cord / Translated by F.S. Arnold. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    The upper extremities are, as a rule, only very slightly affected in cerebellar ataxia ; in some cases they appear to escape altogether. Some degree of uncertainty in the action of grasping with the hand is, however, observed in most cases. The upper extremities are little subject to the co- ordinating influence of the cerebellum, for the reason that they have little to do with the maintenance of equilibrium. Occasionally, however, one can prove the existence of a latent disturbance of co-ordination by a kind of artifice. The patient is told to carry out in rapid succession move- ments of antagonistic muscles—e.g., movements of prona- tion and supination. If cerebellar ataxia be present, the patient will often prove unable to carry out the order, to bring about so subtle a co-operation between antagonist muscles. This abnormality is termed adiadochokiriesia (hia^.oxn^ succession). The spino-cerebellar tracts form the afferent or centri- petal limb of a reflex arc, regulative, not only of muscular movements, but also of muscular tone. Their experimental section causes, in addition to ataxia, hypotonus in the mus- culature of the extremities on the affected side. It is not to be wondered at, then, that, as a rule, cerebellar ataxia is accompanied by cerebellar hypotonus. This cerebellar hypotonus can be demonstrated, like the spinal hypotonus due to lesions of the posterior root system, by palpation, by testing with resisted movements, and by the possibility, owing to loss of tone in antagonizing muscles, of putting the limbs in abnormal positions (vide supra, p. 18). While, howwer, as we have seen, spinal hypotonus is accompanied by impairment or abolition of reflexes, cerebellar hypotonus is independent of the condition of the reflexes. After ablation of one lateral lobe of the cerebellum in man (operation for cerebellar tumours), the reflexes, even if absent immediately after the operation, soon return, sometimes in exaggerated degree, the condition of hypotonus, on the other hand, persisting. Somewhat different, indeed, are the conditions obtaining in these pure cases of cere- bellar lesion (comparable to those produced in animal experi- mentation) from those found in cerebellar diseases which encroach on space, and so cause pressure {e.g., tumours). Here one finds, not infrequently, abolition of tendon reflexes,