Manual of Surgery Volume II Part 42

V. _Trigeminal Nerve._--The most important surgical affection of this nerve is "trigeminal neuralgia," which has already been described (Volume I., p. 373). One or other of the divisions of the nerve may be torn in fractures of the base of the skull, and there results anaesthesia in the area supplied by it. In fractures crossing the apex of the petrous portion of the temporal bone, the great and small superficial petrosal nerves may be ruptured, and the soft palate and uvula are paralysed and there is difficulty in swallowing; there are also painful sensations in the ear. When the ophthalmic division is implicated, the conjunctiva is rendered insensitive, and conjunctivitis, which may be followed by ulceration of the cornea, results from exposure to dust and other foreign bodies, which, on account of the anaesthetic condition of the eye, are allowed to remain and cause irritation.

VI. _Abducens Nerve._--This nerve, which supplies the lateral rectus muscle, has the longest course within the skull of any of the cranial nerves. In spite of this fact, it is comparatively seldom torn in basal fractures; but it is p.r.o.ne to be pressed upon by tumours, gummas, or aneurysms in the region of the base of the brain. When it is paralysed, medial strabismus results.

VII. _Facial Nerve._--Paralysis of the facial muscles, more or less complete, is the most characteristic symptom of lesions of this nerve.

_Paralysis of the Cerebral Type._--When the fibres of the nerve are implicated in any part of their course between the cortical centre and the nucleus in the lower part of the pons, the paralysis is of the upper neurone (cerebral) type. It affects the side of the face opposite to that of the lesion, and the defective movement is more marked in the lower than in the upper half of the face.

This form of facial paralysis may be due to the pressure of an intra-cranial tumour, abscess, or haemorrhage, or to degenerative processes in the cerebral tissue, and as a rule other cranial nerves are also affected. Its recognition is chiefly of diagnostic and localising importance.

_Paralysis of the Peripheral Type._--When the trunk of the nerve is implicated between the pontine nucleus and its peripheral distribution, the paralysis is of the lower neurone (peripheral) type, the muscles on the same side as the lesion being flaccid and atrophied.

The majority of cases are of the so-called "rheumatic" variety, and are attributed to exposure to cold. Others result from fractures implicating the middle fossa of the skull, or are a.s.sociated with chronic suppuration in the middle ear.

In fractures pa.s.sing across the petrous temporal, the nerve may be torn at the time of the injury, or may become pressed upon by a traumatic effusion or by callus later, but considering the frequency of these fractures it is comparatively seldom damaged.

Suppurative disease of the middle ear is a more common cause of facial paralysis. The nerve, as it traverses the facial ca.n.a.l (aqueductus Fallopii), may be pressed upon by inflammatory effusions or granulations, or may be destroyed by the suppurative process, particularly in young children, as in them the osseous wall of the aqueduct is very thin. It may also be involved in tuberculous and in malignant disease of the middle ear.

The nerve may be injured also in the course of operations on the mastoid or middle ear, or in the removal of tumours or glands in the parotid region. As the nerve breaks up into numerous branches soon after it leaves the stylo-mastoid foramen, the paralysis may be confined to one or more of its branches.

Temporary paralysis may result from inflammatory conditions such as parot.i.tis, or from blows or pressure over the nerve, for example by the forceps in delivery.

_Symptoms._--In complete unilateral _facial paralysis_ (Bell's paralysis) the affected side of the face is expressionless and devoid of voluntary or emotional movement. The muscles are flaccid, the cheek is flattened and smooth, all its folds and wrinkles being obliterated. When the patient speaks or smiles, the face is drawn to the sound side (Fig. 201). The eye on the affected side cannot be closed, and on making the attempt the eyeball rolls upwards and outwards. The lower lid droops, the patient cannot wink, and the conjunctiva therefore becomes dry, and is irritated by exposure to cold and dust. The tears run over the cheek. From paralysis of the buccinator muscle there is inability to whistle or to puff out the cheeks and food collects between the cheek and the gums. The orbicularis oris being also paralysed, the patient is unable to show his upper teeth, and the l.a.b.i.al consonants are p.r.o.nounced indistinctly. The sense of taste is often impaired from involvement of the chorda tympani nerve.

[Ill.u.s.tration: FIG. 201.--Patient suffering from left facial Paralysis. Note smoothness of left side of face, imperfect closure of left eye, and deviation of face to right side.

(From a photograph lent by Dr. Edwin Bramwell.)]

When the paralysis is bilateral, the symmetrical appearance of the face renders the condition liable to be overlooked.

_Treatment._--In addition to removing the cause, when this is possible, recovery of function may be promoted by the administration of drugs, such as pota.s.sium iodide, strychnin, or iron, by the application of blisters, or by ma.s.sage and electricity. These measures are most useful in cases due to blows or exposure to cold. When the nerve is accidentally divided in the course of an operation on the face, it should immediately be sutured. So long as the electrical reactions of the affected muscles indicate an incomplete lesion, recovery may be confidently expected (Sherren). When the reaction of degeneration is present and the paralysis has lasted for more than six months, there is little hope of recovery, and recourse should be had to operation, to restore the function of the nerve by grafting its distal end on to the trunk of the hypoglossal nerve. To prevent paralysis of the tongue the lingual nerve may be divided, and its proximal end anastomosed with the distal end of the hypoglossal.

The facial may be grafted on the accessory nerve, but the a.s.sociated movements of the face which then accompany movements of the shoulder often prove inconvenient.

_Facial Spasm._--Clonic contraction of the facial muscles (histrionic spasm) occasionally results from irritative lesions in the cortex or pons. Sometimes all the muscles are involved, sometimes only one, for example the orbicularis oculi (palpebrarum)--blepharospasm. This condition may be induced reflexly from irrigation of the trigeminal nerve, notably of branches that supply the nasal cavities and the teeth.

The _treatment_ consists in removing any source of peripheral irritation that may be present, in employing ma.s.sage, and in administering nerve tonics, bromides, and other drugs. In severe cases, the facial nerve may be stretched with benefit, either at its exit from the stylo-mastoid foramen or on the face.

VIII. _Acoustic_ or _Auditory Nerve_.--The acoustic nerve is liable to be damaged along with the facial in tumours of the cerebello-pontine angle, and in fractures which traverse the internal auditory meatus.

Both nerves also may be torn across just before they enter the meatus in severe brain injuries apart from fracture. Complete and permanent deafness results. Effusion of blood into the nerve sheath, or into the internal or middle ear, causes transitory deafness, and the patient suffers from noises in the ear, giddiness, and interference with equilibration.

IX. The _Glosso-pharyngeal Nerve_ is comparatively seldom injured.

When it is compressed by a tumour in the region of the medulla, there is interference with speech and deglut.i.tion, ulcers form on the tongue, and dema of the glottis may supervene.

X. The _Vagus_ or _Pneumogastric Nerve_ is seldom injured within the cranial cavity.

In the neck, it is liable to be divided or ligated in the course of operations for the removal of malignant or tuberculous glands, for goitre, or for ligation of the common carotid. Division of the nerve on one side, or even removal of a portion of it, is not as a rule followed by any change in the pulse or respiration. If it is irritated, however, for example by being grasped with an artery forceps, there is inhibition of the heart, and if it is accidentally ligated, there may be persistent vomiting.

Division of the main trunk, or of its recurrent branch on one side, results in paralysis of the corresponding posterior crico-arytaenoid muscle--the muscle that opens the glottis. This condition is known as unilateral _abductor paralysis_, and is accompanied by interference with inspiration and phonation. If both nerves are divided, bilateral abductor paralysis results: the vocal cords flap together, producing a crowing sound on inspiration and embarra.s.sment of breathing, and tracheotomy may be necessary to prevent asphyxia.

The vagus and recurrent nerves have been successfully sutured after having been divided accidentally.

XI. _Accessory_ or _Spinal Accessory Nerve_.--This nerve is seldom damaged within the skull. It supplies the sterno-mastoid and trapezius; but as these muscles usually have an additional nerve supply from the cervical plexus, the accessory may be divided, or a considerable portion of it resected, as, for example, in the treatment of spasmodic torticollis, without any serious disablement resulting.

It is liable to be accidentally divided in excising malignant or tuberculous glands in the neck. When, however, the accessory is the only source of supply to these muscles, its division is followed by considerable disablement, which appears to depend almost entirely on the _paralysis of the trapezius_. The head is inclined slightly forward, the shoulder is depressed, the arm hangs heavily by the side and is slightly rotated forward, the scapula is drawn away from the spine and rotated on its horizontal axis, and there is slight cervical scoliosis with the concavity towards the affected side. The trapezius is markedly wasted, and is, therefore, less prominent in the neck than normally, and the functions of the arm and shoulder are impaired, especially in making overhead movements. In time other muscles compensate in part for the loss of the trapezius.

When divided accidentally, the nerve should be immediately sutured.

Even when the paralysis has lasted for some time, secondary suture should be attempted; if this is impossible, the peripheral end should be anastomosed with the anterior primary divisions of the third and fourth cervical nerves (Tubby). Ma.s.sage, electricity, and the administration of tonics are also indicated.

XII. _Hypoglossal Nerve._--This nerve has been ruptured in fractures pa.s.sing through the ca.n.a.lis hypoglossi (anterior condylar foramen). It is also liable to be divided in wounds of the submaxillary region--for example, in cut throat, or during the operation for ligation of the lingual artery, or the removal of diseased lymph glands.

The paralysed half of the tongue undergoes atrophy. When the tongue is protruded, it deviates towards the paralysed side, being pushed over by the active muscles of the opposite side. Speech and mastication are interfered with, the tongue feeling too large for the mouth; in time this disability is to a large extent overcome.

#The Cervical Sympathetic.#--The cervical sympathetic cord and its ganglia may be injured in the neck by stabs or gun-shot wounds, or in the course of deep dissections in the neck; and in injuries of the lower part of the cervical enlargement of the spinal cord (p. 417) or of the first dorsal nerve root.

Paralysis of the cervical sympathetic is characterised by diminution in the size of the pupil on the affected side. The pupil does not dilate when shaded, nor when the skin of the neck is pinched--"loss of the cilio-spinal reflex." The palpebral fissure is smaller than its fellow, and the eyeball sinks into the orbit. There is anidrosis or loss of sweating on the side of the face, neck, and upper part of the thorax, and on the whole upper extremity of the affected side.

CHAPTER XV

DISEASES OF THE CRANIAL BONES

Suppurative periost.i.tis and osteomyelitis--Tuberculosis-- Syphilis--Tumours.

#Suppurative Periost.i.tis and Osteomyelitis.#--These conditions may be the result of infection through the blood stream, but as a rule they follow upon a breach of the surface caused by a wound, a severe burn as in epileptics, a tertiary syphilitic ulcer, or a compound fracture that has become infected. Sometimes they follow suppuration in the middle ear and mastoid or in the frontal sinus, and epithelioma and rodent cancer that has ulcerated and become infected after spreading from the face towards the vertex. They are occasionally a.s.sociated with acute cellulitis of the scalp. When the infection is blood-borne suppuration occurs on both aspects of the bone--a point of importance in treatment.

The illness is usually ushered in by a rigor, and this is soon followed by other signs of suppuration--high temperature, pain and tenderness, and the formation of a fluctuating swelling in relation to the bone. When pus forms between the bone and the dura, there is a characteristic dema of the overlying area of the scalp--spoken of as _Pott's puffy tumour_--which is of value as indicating the extent of the disease in the bone, and of the collection of pus between it and the dura. When suppuration occurs under the pericranium, an incision gives exit to a quant.i.ty of pus, and exposes an area of bare bone. If the incision is made early, this bone may soon be covered by granulations and recover its vitality; but if operation is delayed, it usually undergoes necrosis. The sequestrum that forms includes, as a rule, only the outer table, but in some cases the whole thickness of the bone undergoes necrosis. In either case the separation of the sequestrum is an exceedingly slow process, and is not accompanied by the formation of new bone. When the whole thickness of the skull is lost, there may be a protrusion of the contents of the skull--hernia cerebri; should the patient survive, the gap becomes filled in by a dense fibrous membrane which is fused with the dura mater.

Serious complications, in the form of meningitis, cerebral abscess, sinus phlebitis, and general pyaemia, are liable to develop at any time during the progress of the infection, and we have seen pyaemia develop after the suppuration in the skull had been recovered from.

_Treatment._--Early, free, and, if necessary, multiple incisions are indicated to admit of disinfection of the affected area, and of the establishment of drainage. If the symptoms point to suppuration having occurred between the bone and the dura, the skull should be trephined and further bone removed with the rongeur forceps as may be required.

Time may be saved by separating the sequestrum with the aid of an elevator or sharp spoon, or by chiselling away the dead part till healthy vascular bone is reached.

#Tuberculosis# of the cranial vault is usually met with in children.

The disease commences in the diploe, and results in the formation of a central sequestrum, around and beneath which the tuberculous process spreads. Granulations form between the skull and the dura, and on the outer aspect lifting up the pericranium. The sequestrum is slowly thrown off, and when separated is circular like a coin and presents worm-eaten edges.

A circ.u.mscribed, tender swelling forms, at first yielding an obscure sensation of fluctuation, but later, when the pus is no longer confined under the pericranium, a.s.suming the characters of a cold abscess, which gradually becomes superficial, and eventually bursts through the scalp, forming one or more sinuses.

The abscess should be laid open, all tuberculous granulations sc.r.a.ped away, and the sequestrum removed, with the aid of the chisel if it has not already become loose. On inserting the finger through the opening, it appears to penetrate to an alarming extent; this is due to the acc.u.mulation of tuberculous material between the skull and the dura mater, depressing the latter. After healing is completed, a depression or gap in the bone remains.

#Syphilis.#--Syphilitic affections occur during the tertiary period of the disease, and usually implicate the frontal and parietal bones (Fig. 202). They are described in Volume I., p. 462.

[Ill.u.s.tration: FIG. 202.--Skull of woman ill.u.s.trating the appearances of Tertiary Syphilis of Frontal Bone--Corona Veneris--in the healed condition.]

#Tumours.#--_Osteoma_ of the skull has been described with diseases of bone (Volume I., p. 481).