Book - The Pineal Organ (1940) 30
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Gladstone RJ. and Wakeley C. The Pineal Organ. (1940) Bailliere, Tindall & Cox, London. PDF
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The Pineal Organ
Chapter 30 Symptomatology Of Pineal Tumours
Enlargements of the pineal gland usually present clinically a welldefined syndrome. Owing to the anatomical position, enlargements of the gland cause pressure on structures which give rise to clear-cut clinical symptoms and hence are quite early recognizable.
The symptoms can best be considered under three headings : (1) Focal
Fig. 286. — Anatomical Relationships of the Pineal Gland.
— those due to the lesion itself. (2) Local — the changes brought about within the central nervous system. (3) General — the somatic changes which sometimes accompany such enlargements.
1 . Focal Signs. — The focal signs which may be produced by tumours are due in the main to the anatomical position of the gland (see Fig. 286). It is because of its relationship to the superior corpora quadrigemina that the eye signs produced are so characteristic.
The aqueduct of Sylvius lying below the gland is very liable to be occluded and produce a severe degree of internal hydrocephalus when pressed upon by a pineal tumour.
The cerebellum lies immediately posterior to the pineal and is often invaded by growths arising in that neighbourhood.
A contributory factor in the production of the internal hydrocephalus is the fact that the vein draining the choroid plexuses — the vein of Galen — is very liable to be compressed, with the result that engorgement of the
Fig. 287. — Schematic Representation of the Various Ways in which a Pineal Tumour may extend and cause Pressure Symptoms : (1) on the Corpora Quadrigemina ; (2) on the Aqueduct of Sylvius and Midbrain ; (3) downwards on the Cerebellum, causing Cerebellar Symptoms ; (4) on the Midbrain Thalamic and Subthalamic Regions ; and (5) on the Cerebral Hemisphere.
choroid plexuses is produced and possibly an increased secretion of the cerebrospinal fluid.
Tumours which arise in the pineal may extend in various directions, and Fig. 287 illustrates the common methods of extension.
Eye Signs. — Tumours may extend into the corpora quadrigemina and oculomotor region and produce a clinical syndrome which is characterized by loss of pupillary reaction to light, reaction to accommodation, and upward, downward, and lateral movement of the eyes, in that order of development. It is extremely common to find that the light reflex is absent and the patient unable to look upward.
To understand this clearly it is necessary to visualize the arrangement of the oculomotor nuclei (Fig. 288). It will be remembered that the nuclei of the Illrd, IVth, and Vlth nerves lie in about one continuous line on either side of the aqueduct just below the corpora quadrigemina, together with the medially placed nuclei. Various functions have been mapped out for the several parts of the nucleus. In Fig. 288 it will be seen that the Edinger-Westphal nucleus (A) is the most anterior, and is concerned with control of the pupillary and ciliary muscles ; the dorsilateral nucleus (B) is concerned with upward movements ; the ventromedial nucleus (C) is concerned with downward movement ; the central nucleus with movements of divergence. The small caudal nucleus (D) may be concerned again with pupillary reaction.
Fig. 288. — Diagram showing Arrangement of Oculomotor Nuclei.
Thus it will be seen that pressure exerted from in front and above the nuclei will give rise first to absence of light reflex, then to loss of accommodation and loss of upward and downward movement. In clinical practice it is the lateral movements which persist for the longest period.
Ear Signs. — Should the inferior corpora quadrigemina be pressed upon, then deafness, unilateral or bilateral, complete or partial, may result.
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 incoordination, with a tendency to swerve to the side most affected, or, if in the midline, a tendency to fall backward. There is weakness, adiadochokinesia, 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 pastpointing 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 control 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 of papilledema, which is usually very marked and presents itself as a very early sign. Epileptiform fits also occur.
Signs are produced in the cranial nerves as the result of the raised intracranial pressure. The third ventricle is commonly affected, and double vision and strabismus are frequently present. The Vlth nerve is also involved. There is paralysis of the external rectus on either or both sides, with a convergent strabismus. The olfactory nerve is not affected. The Vth nerve may be affected, giving rise to a weakness of the muscles of mastication and sometimes sensory loss on that side of the face. .
Facial paralysis is seen quite commonly, and is either produced by the local extension of the growth or from damage to the nerve resulting from the raised intracranial pressure.
Deafness is common, and has already been mentioned.
The nerves IX, X, XI, and XII are not usually affected ; only if the cerebellum is extensively invaded will they be pressed upon and give rise to their characteristic physical signs.
3. General Signs. — Pineal tumours associated with general somatic changes are almost confined to the male sex. The disturbances of growth associated with pineal tumours affect chiefly the genital organs, but are often associated with adiposity and sometimes with general and symmetrical overgrowth.
Hypertrophy of the penis and testes, with growth of pubic hair and precocious sexual instinct, have been observed with most tumours classed as teratornata, as well as with simple, benign, and malignant tumours. The testicles show a marked increase in the size and number of the interstitial cells. The breasts enlarge, and one case has been reported of a secretion of colostrum in a boy aged 4, associated with testicular enlargement.
Increase of hair occurs also on the lips and chin and in the axillae. Deepening of the voice may take place.
The adiposity which occurs has been observed with all varieties of pineal tumours, and cannot be distinguished clinically from hypophyseal obesity — probably because, as already pointed out, it is in both cases due to hypothalamic involvement. The adiposity is proximal in distribution ; it is marked over the shoulders and pelvic girdles, with considerable enlargement of the breasts. The buttocks, thighs, and abdomen also show heavy deposits of fat.
Physiological experiments seem to point to the fact that injection of pineal extracts in chicks and guinea-pigs causes a general increase in size, with genital overgrowth and sexual precocity, but the evidence is still not completely convincing.
The possibility is that the pineal gland normally facilitates growth in
440 THE PINEAL ORGAN
general, and sexual development in particular. Acceleration of these functions occurring in the course of pineal tumours may therefore be interpreted as hyperpinealism. In the absence of further data, obesity and hypertrichosis may be considered as part of the general and sexual overgrowth, but the hypophyseal failure must be considered as a possible contributing factor in the adiposity.
A close relationship evidently exists between the pineal and testicular functions, which are probably not antagonistic in nature, but as yet there are insufficient data to define the relationship between the pineal organ and the ductless glands, and hence of its relationship to the gonads. Moreover, in quite a number of cases there are no signs whatever of any sexual abnormalitv.
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Cite this page: Hill, M.A. (2024, April 25) Embryology Book - The Pineal Organ (1940) 30. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_The_Pineal_Organ_(1940)_30
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
