The Surgery of the Skull and Brain

by Louis Bathe Rawling

Localizing to the pre- and post-central convolutions.

Injury to the pre-central or motor area usually leads to the development of definite symptoms—twitchings, convulsions, or paralysis of the face and extremities on the contra-lateral side. In the earlier stages reflexes are abolished. Later on, as the result of degenerative changes in the pyramidal tracts, spasticity, contractures, and rigidity, with increased reflexes will be observed in the affected limbs. On the other hand, the muscles do not show any reaction of degeneration. Babinski’s sign is generally present.

Injury to the post-central convolutions might be expected to lead to various alterations in tactile and muscle sense, in stereognosis, and in sense of pain and temperature, but the general condition of the patient seldom permits accurate demonstration. Such sensory disturbances are more frequently observed as late results of head-injury.

Localizing of the occipital lobes.

Laceration of the occipital lobes may lead to homonymous hemianopia, for which defect it is probable that the degree of laceration must be considerable, involving mainly the mesial aspect of the occipital lobe (see [Fig. 69]). Schäfer has shown that the greater portion of the occipital lobe may be removed in monkeys without producing loss of vision, and it is only when the lesion involves the parieto-occipital fissure and passes into the occipito-temporal convolutions that loss of vision is permanent.

Slighter degrees of occipital injury may lead to subjective symptoms, such as flashes of light, colour changes, &c.

Localizing to the cerebellum.

Lesions of the cerebellum rarely permit of the development of such localizing symptoms as are observed in cerebellar tumours. Inco-ordination of movement, ataxia, and other symptoms observed in cerebellar tumour formation are, from the general condition of the patient, incapable of demonstration in cerebellar laceration. It is necessary, however, to draw attention to the significance of yawning and gaping. This symptom has been observed in several recent cases, and, as far as my observation goes, is only present in cerebellar lesions.

Fig. 58. The Cortical Motor and Sensory Areas.