#Micrencephaly.#--This condition is due to defective development of the brain, and not to premature closure of the cranial sutures and fontanelles, and as the subjects of it are mentally deficient, and often blind, deaf and dumb, the removal of segments of the skull with a view to enable the brain to develop have proved futile.
CEREBRAL TUMOURS
As a comparatively small proportion of tumours of the brain--using the term "tumour" in its widest sense--are amenable to surgical treatment, it is only necessary here to refer to those aspects of this subject that have a distinctively surgical bearing.
Various forms of growth occur in the brain, the most common being tuberculous nodules, syphilitic gumma, endothelioma, glioma, and sarcoma. Less frequently fibroma, osteoma, and parasitic, haemorrhagic, and other cysts are met with. The growth may originate in the brain tissue primarily, or may spread thence from the membranes, or from the skull. In relation to operative treatment, it is an unfortunate fact that those forms that are well defined and do not tend to infiltrate the brain tissue, usually occur at the base, where they are difficult to reach; while those that develop in more accessible regions are for the most part infiltrating growths of a gliomatous or sarcomatous nature, and are therefore irremovable.
_Clinical Features._--The presence of a tumour in the brain inevitably results sooner or later in an increase in the intra-cranial tension, and to this the symptoms are chiefly due.
The earliest and most prominent of the _general symptoms_ are severe paroxysmal headache, optic neuritis, with choked disc and limitation of the field for blue, amounting sometimes to blue-blindness (Cushing). The relative degree of neuritis in the two eyes is a reliable guide to the side on which the tumour is situated (Horsley).
The symptoms are seldom absent, and are common to all forms of tumour, wherever situated. Vomiting, which is without relation to the taking of food and is usually unattended by nausea, is a characteristic symptom when present, but it is wanting in two-thirds of the cases (Cushing). Vertigo, general convulsions, and signs of mental deterioration are also present in a considerable proportion of cases.
In addition, certain _localising symptoms_ may be present. When, for example, the tumour is situated in the _cortex of the Rolandic area_, attacks of Jacksonian epilepsy, preceded by an aura, which is usually referable to the centre primarily implicated, are common. The group of muscles first involved, and the order in which other groups become affected, are important localising factors. As the tumour increases in size, these irritative phenomena are replaced by localised paralyses.
The tactile and muscular sensations are also disturbed, and motor and sensory aphasia may be present. In some cases localised tenderness on percussing the skull may be of a.s.sistance in indicating the site of the tumour.
When the tumour is _sub-cortical_, that is, in the centrum ovale, there are no Jacksonian spasms, the motor paralysis is more widespread, and sensation also is lost on the opposite side of the body. There is no special tenderness on percussion. It is not always possible, however, to distinguish between cortical and sub-cortical tumours, and in many cases both areas are invaded.
Tumours situated in the region of _the internal capsule_, and _in the deeper parts of the brain_, are not attended with Jacksonian spasms, paralysis develops more rapidly than in cortical and sub-cortical tumours, and there is complete loss of sensation on the opposite side of the body. The cranial nerve-trunks also are liable to be pressed upon.
Tumours and cysts _in the cerebellum_ give rise to symptoms similar to those of cerebellar abscess (p. 381).
Tumours _in the cerebello-pontine angle_, in addition to the special symptoms a.s.sociated with cerebellar lesions, give rise to symptoms of interference with nerve-roots of the same side. The facial and acoustic nerves are most frequently affected, resulting in facial weakness, tinnitus, loss of perception for high-pitched notes, as tested by Galton"s whistle, or absolute unilateral deafness. Any of the other cranial nerves from the fifth to the twelfth may be either irritated or paralysed. Pressure on the pons may produce hemiplegia of the opposite side, with spasticity and exaggeration of reflexes.
Sudden death may occur from crowding of the cerebellum into the foramen magnum.
With the growth of the tumour the symptoms become aggravated, the optic neuritis is followed by optic atrophy and blindness, the patient gradually becomes stuporous, and finally dies in a state of coma. The severity of the symptoms depends to a large extent on the rapidity of growth of the tumour; thus an osteoma growing slowly from the inner table of the skull and implicating the brain may reach a considerable size without producing cerebral symptoms, while a comparatively small sarcoma or syphilitic gumma of rapid growth may endanger life. A sudden and serious aggravation of symptoms may result from haemorrhage into a soft tumour, such as glioma.
The _diagnosis_ of the pathological nature of a cerebral tumour is generally "hardly more than a guess" (Gowers). At the same time it may be borne in mind that _syphilitic gummata_ occur in adults, from forty to sixty years of age, who have suffered from acquired syphilis, and who may present other evidence of the disease. They tend to increase somewhat rapidly. A negative Wa.s.sermann reaction does not necessarily exclude a diagnosis of brain syphilis. Severe nocturnal pain which interferes with sleep is often a prominent symptom. Gummata are generally situated on the surface of the brain; they often originate in the dura mater, and when exposed are easily enucleated. Improvement in the symptoms may follow the administration of iodides and mercury, or organic a.r.s.enical salts of the salvarsan group, but in many cases the growth is very resistant to anti-syphilitic treatment.
_Tuberculous ma.s.ses_ occur most frequently in children and adolescents, and other signs of tuberculosis are usually present. The cerebellum is a common seat of these tumours, and they are often multiple. Their growth may be rapid at first, and then become arrested for a time. Spasmodic growth of a tumour strongly suggests its tuberculous nature, and superadded signs of basal meningitis confirm the diagnosis.
_Endothelioma_ grows from the dura mater, and in so far as it is a well-defined and non-infiltrating growth it lends itself to removal by operation. Unfortunately, however, it is usually located at the base of the brain and is not readily accessible.
_Glioma_ is usually met with in the young; it tends to grow slowly at first, but may take on a rapid growth at any time, and haemorrhage is liable to occur into the substance of the tumour, causing a sudden aggravation of the symptoms.
_Sarcoma_ occurs between p.u.b.erty and middle life; it grows slowly, and compresses rather than destroys the brain tissue. It is sharply defined from the surrounding cerebral tissue, and is therefore more favourable for operation than glioma.
The _prognosis_ is grave in all forms of brain tumour. Even in syphilitic growths, although the more urgent symptoms may be ameliorated by the use of drugs, recurrence is liable to occur, and the structural changes induced in the cerebral tissue, and the contraction of the cicatrix which results, may permanently interfere with the functions of the brain, or may induce Jacksonian epilepsy.
Tuberculous tumours also may become arrested, and may cease for a time to cause symptoms, but permanent cure is extremely rare. We have known a sarcoma to recur as late as five years after removal. Death sometimes occurs suddenly from haemorrhage, from acute dema, or from implication of vital centres.
_Treatment._--It is to be borne in mind that gummatous growths in the brain are seldom influenced to any extent by anti-syphilitic remedies, and time should not be wasted in trying this form of treatment.
The question of removal by operation arises in cases in which there is reason to believe that the tumour is situated near the surface of the brain and that it is circ.u.mscribed and of moderate size. Unfortunately it is only in a small proportion of cases that these conditions are present and can be recognised before opening the skull.
In many cases in which there is no hope of being able to remove the tumour, it is advisable to relieve symptoms due to excessive intra-cranial tension, such as blindness, severe headache, and persistent vomiting, by performing a "decompression operation"
(_Operative Surgery_, p. 108). The relief that follows such operations is often remarkable.
Lumbar puncture, frequently repeated, has also been practised for the relief of tension in inoperable cases, but it is not free of danger and is not to be looked upon as a subst.i.tute for a decompression operation.
When surgical treatment is contra-indicated, all that can be done is to palliate the symptoms by bromides, opium, phenacetin, caffein, and other drugs.
#Tumours of the Pituitary Body# or #Hypophysis Cerebri#.--The tumours most frequently met with in the pituitary body are of the nature of adenoma with hyperplasia and cystic degeneration; carcinoma and sarcoma also occur. They develop slowly and give rise to comparatively slight increase in the intra-cranial tension. When the anterior lobe is implicated and there is a pathological increase in the functional activity of the gland (_hyperpituitarism_), signs of acromegaly may ensue. Diminution of function (_hypopituitarism_) is attended with infantilism, a rapid deposition of fat in the subcutaneous tissue, and a decrease or loss of the genital functions. In women, amenorrha is an early and constant symptom. Intense drowsiness is a marked feature in some cases.
From their position close to the back of the optic chiasma these growths affect the fibres pa.s.sing to the nasal half of each retina, and so give rise to bilateral temporal hemianopsia, and although there is no choked disc, the optic nerves undergo primary atrophy from pressure, and there is failure of sight.
Marked temporary benefit has followed the administration of thyreoid extract. Operative treatment has been successful in a number of cases, but as the anterior lobe is essential to life, the operation is merely directed towards the relief of pressure on the optic chiasma with a view to preventing loss of vision. We have seen marked relief follow a temporal decompression operation.
#Epilepsy.#--The surgical aspects of Jacksonian epilepsy following head injuries have already been considered (p. 358). For the cure of those forms of epilepsy in which there is no gross lesion of the brain, numerous surgical procedures have been suggested, but from none of these have the results been encouraging.
#Hernia Cerebri.#--This term is applied to a protrusion of brain substance through an acquired opening in the skull and dura mater, such as may result from a compound fracture or a gun-shot wound. The protrusion is due to increased intra-cranial tension, and is almost invariably a.s.sociated with infection of the brain and its membranes, and with the presence of a foreign body or fragments of bone. Other things being equal, a hernia is more likely to occur through a small than through a large opening in the skull.
So long as the extruded portion of brain matter is small, it pulsates, but as it increases in size and is pressed upon by the edges of the opening through which it escapes, the pulsation ceases, and the herniated portion may become strangulated and undergo necrosis.
In cases of compound fracture, and in other conditions a.s.sociated with necrosis of bone, ma.s.ses of redundant granulation tissue growing from the soft parts outside the skull may simulate a hernia cerebri.
The _treatment_ consists in counteracting the septic infection by purifying the protruding ma.s.s, and if necessary by enlarging the opening in the skull with rongeur forceps to admit of the removal of foreign bodies or bone fragments and to relieve the inter-cranial tension. Steps must also be taken to prevent meningitis, which, if it occurs, is usually fatal. Pressure over the hernia, with the object of returning it to the skull, is to be avoided, and the herniated portion should not be cut away unless it is sloughing, or has become pedunculated. It may be got rid of by painting it with 40 per cent.
formalin, which causes a dry, h.o.r.n.y crust to form on the surface; this is picked off, and the formalin re-applied.
After the hernia has disappeared and the wound is aseptic, steps should be taken to close the gap in the skull. This may be done by an osteo-plastic operation in which a flap, comprising a segment of the outer table, is raised from an adjacent part of the skull and placed in the gap; or by transplanting a portion of periosteum-covered bone from the scapula, tibia, or other suitable source. An alternative method is to implant a plate of celluloid, silver or other metal, or a portion of the fascia lata, in the gap. When a permanent hole is left in the bone, the patient should wear over it a leather or metal shield to protect the brain.
The protrusion of brain resulting after a decompression operation deliberately performed for the relief of intra-cranial tension, unless it becomes infected, has nothing in common with a hernia cerebri.
SURGICAL AFFECTIONS OF THE CRANIAL NERVE
Irritation, or paralysis, of one or more of the cranial nerves may result from lesions implicating their centres or trunks.
When the trunk of the nerve is affected, the paralysis is on the same side as the lesion, and is of the lower neurone type; when the cortical centre or the upper axons are involved, it is on the opposite side, and is of the upper neurone type (p. 334). The lesions of the cerebral centres with which nerve symptoms are most frequently a.s.sociated are: laceration of the brain, haemorrhage, meningitis, tumour, and syphilitic gumma.
The nerve-trunks may be contused or torn across, especially in basal fractures which traverse their foramina of exit; blood may be effused into their sheaths as a result of injuries not attended with fracture; or they may be pressed upon by an inflammatory effusion, a tumour, a gumma, or an aneurysm invading the base of the skull. When the nerve is merely contused, or pressed upon by blood-clot, the paralysis tends to pa.s.s off in the course of a few days. When it is torn across, or compressed by a new growth, the paralysis is permanent. In some traumatic cases paralysis does not come on until a few days after the injury, and is then due either to gradually increasing pressure from blood-clot, or more probably to the onset of meningitis or of ascending neuritis.
I. The branches of the _Olfactory Nerve_ may be ruptured as they pa.s.s through the cribriform plate in fractures implicating the anterior fossa of the skull, and there results complete and permanent loss of smell (_anosmia_). Haemorrhage into the nerve sheath or contusion of the nerve may cause a transitory loss of smell. The trunk of the nerve may be implicated also in tumours and meningitis in the anterior fossa. In all cases in which anosmia results there is also interference with the power of recognising different flavours, thus greatly impairing the sense of taste.
II. _Optic Nerve._--Temporary paralysis of one or both optic nerves is a comparatively common result of traumatic effusion of blood into their sheaths; the resulting blindness may pa.s.s off in a few days, or may last for some weeks. When a large effusion takes place, the prolonged pressure on the nerve may result in optic atrophy and permanent blindness. Complete severance of the nerve by a bullet, the point of a sharp instrument, or a fragment of bone, results in loss of sight in the eye on the same side. In cellulitis of the orbit, intra-orbital tumour, gumma and aneurysm in the region of the cavernous sinus, also, the optic nerve may be implicated.
Lesions implicating the cortical centre for sight in the occipital lobe give rise to hemianopia--that is, loss of sight in the lateral halves of the fields of vision of both eyes--colour-blindness, subjective sensations of light and colour, and other eye symptoms.
Double optic neuritis, followed by optic atrophy, is one of the most constant effects of the growth of a tumour within the skull, and is not uncommon in cases of cerebral abscess and meningitis. Pressure on the optic chiasma, for example by a tumour of the pituitary body, is a.s.sociated with bilateral temporal hemianopsia.
III. _Oculo-Motor Nerve._--One or more of the branches of this nerve may be compressed by extravasated blood, or be contused and lacerated in fractures implicating the region of the sphenoidal fissure. Fixed dilatation of one pupil may result from pressure by blood-clot, without other functional disturbance of the nerve. A tumour or an aneurysm growing in this region also may press upon the nerve.
Sometimes both nerves are involved--for example, in fracture implicating both sides of the anterior fossa, and in tumours, particularly gumma, growing in the region of the floor of the third ventricle. In lesions of the cerebral hemispheres the third nerve is frequently paralysed. Its cortical centre lies in close proximity to the centre for the face (Fig. 179).
The most prominent symptoms of complete paralysis are ptosis or drooping of the upper eyelid, lateral strabismus, and slight downward rotation of the eye with diplopia. There are also dilatation of the pupil from paralysis of the circular fibres of the iris, and loss of accommodation and reaction to light from paralysis of the ciliary muscle.
Paralysis of the muscle supplied by the third nerve is frequently a.s.sociated with paralysis of other ocular muscles. When all the muscles of the eye are paralysed, the condition is known as "opthalmoplegia externa"; it is usually due to syphilitic disease in the floor of the third ventricle.
IV. The _Trochlear_ or _Patheticus Nerve_, which supplies the superior oblique muscle, may suffer in the same way as the oculo-motor nerve.
When it is paralysed, there is defective movement of the eye downward and medially, and the patient may complain of diplopia when he looks downward.