438 THE PINEAL ORGAN 



Cerebellar Signs. — Extension occurs into the cerebellum. This may 

 be into either hemisphere or directly in the midline. 



Nystagmus is very common ; there is often giddiness and inco- 

 ordination, with a tendency to swerve to the side most affected, or, if in 

 the midline, a tendency to fall backward. There is weakness, adiado- 

 chokinesia, intention tremor in the arms, and usually a grossly ataxic 

 gait. Rombergism may be present. The cerebellar involvement will in 

 some cases also give rise to a dysarthric speech, usually staccato in type. 



Other cerebellar signs may be present. On extension of the hands 

 there is a tendency to fall away on the side of the lesion. The past- 

 pointing test may show deviation. 



The reflexes may be diminished or absent on one or both sides and the 

 limbs atonic, but usually the pyramidal involvement predominates. 



Pyramidal and Sensory Signs. — The pyramidal tracts and medial 

 lemnisci may be affected. Involvement of the pyramidal tracts gives 

 rise to increase in tone on the affected side, weakness, increased deep 

 reflexes, absent abdominal reflexes, and an extensor plantar response. 

 The sensory changes take the form of a hemianesthesia, as all the sensory 

 fibres at the level of the corpora quadrigemina have joined the medial 

 lemniscus. 



Signs of Third Ventricle Involvement. — The somatic changes sometimes 

 associated with pineal tumours have been referred to involvement of the 

 hypothalamus and third ventricle. 



Disturbed temperature regulation has been reported in a few cases 

 of pineal tumour. The hypothalamus is probably concerned in the con- 

 trol of body temperature, and the case reports show that there may be 

 rise of temperature of an irregular type without any apparent source of 

 infection and with no corresponding rise in pulse-rate. The controlling 

 centre in the hypothalamus itself or its efferent pathway may be damaged. 

 Polyphagia, polyuria, and glycosuria have also been observed, and are 

 probably due to hypothalamus involvement. 



Signs of Involvement of the Cerebral Hemispheres. — As a pineal tumour 

 grows, extension occurs upwards into the hemispheres. It is of necessity 

 a deep extension, and the motor cortex and sensory cortex are not usually 

 involved. The optic radiations, however, pass near by on their way to 

 the occipital cortex, and these may be cut through and a right or left 

 homonymous hemianopia result. 



2. Local Signs. — Owing to the site of the lesion, signs due to raised 

 intracranial pressure manifest themselves early in the course of the 

 tumour growth. Headaches are severe and continuous, and are associated 

 with vomiting. Mental lethargy and reduction in mentality may be 

 early signs, as may also giddiness. Loss of vision occurs from the effects 



