Surgical diseases of the nervous system

Surgical diseases of the nervous systemInflammations of the nervous system

Inflammation may involve the nerve system in any region. It may be caused by infections, chem­icals, or toxins, or from unknown causes.

Neuritis literally means inflammation of a nerve; however, this term has been applied loosely to functional involvements of nerves, in the absence of actual inflammation. Treatment is medical.

Meningitis is inflammation of the meninges, the coverings of the brain and spinal cord. Any layer may be involved at any level. Treatment is medical.

Myelitis means inflammation of the spinal cord. Treatment is medical.

Encephalitis is inflammation of the brain proper, frequently referred to as “sleeping sick­ness.” Treatment is medical. Inflammation of both the brain and the spinal cord is called myeloencephalitis.

Tabes dorsalis is a specific infection of the spinal cord caused by syphilis. General paresis is syphilitic infection of the brain.

Brain abscess may occur any place within the brain and may reach any size. It is most often a complication of sinus or mastoid infection, but may occur following injuries. Osteomyelitis of the skull often is associated. Usually the abscesses are single but they may be multiple. Treatment is surgical and entails craniotomy. A few types of abscesses are treated by excision, but in most the abscess cavity is drained of its pus and a drainage device is usually left in place. Anti­biotic drugs are instilled in the cavity, as well as given orally and/or by injection. Progress of the cavity is studied by repeated diagnostic measures, including x-ray contrast films of the abscess cavity. Before the advent of the newer drugs for infections, brain abscesses were almost uniformly fatal. But now recovery is the rule rather than a rarity.

Poliomyelitis (infantile paralysis) is an in­flammation of the nervous system caused by a virus. It affects chiefly the front portion of the spinal cord (motor tracts), but the meninges, the brain, and the brain stem are also involved. It may involve any level. In the early stages the effect on the motor cells causes muscle spasms along with its other inflammatory symptoms. As the cells are destroyed, however, the muscles become flaccid and weak. Paralysis may result. When the brain stem with its vital respiratory center is involved (bulbar polio), respiration may be impaired. In the acute stages there are no operative procedures of value, but when there is residual paralysis of the trunk or extremities various corrective orthopedic procedures may be of value.

Congenital Diseases of the nervous system

In the complicated development of the nervous system in the embryo, various malformations may occur. Often they occur in combinations.

Parts or all of the bony skull may be absent, a condition known as an-encephaly. Occasionally the bony arch of the spinal canal does not com­pletely develop, called spina bifida.

Meningocele is a herniation of the meninges through a bony defect of the spinal canal. There is a fluid-filled mass in the midline of the back lined with the meninge layers and covered with skin. When such a mass contains spinal cord tissue it is called meningomyelocele. In the former malformation surgical correction is much more successful, but when the cord is involved, permanent sensory changes and paralyses may result.

(Hydrocephalus is often congenital but is discussed under the following heading “Other Diseases of the Nervous System.”)

Birth palsies are not uncommon and are thought to be due to injury to the baby in the womb during labor, or at the time of birth. A palsy is a weakness of a muscle or a group of muscles due to an inadequate nerve supply to them. Cerebral palsy is a generalized type due to damage to the brain itself. In spinal palsy the spinal cord has been injured. Defects of the spinal or peripheral nerves are known as nerve palsies. Quite common is an arm palsy called brachial plexus palsy from injury to this net­work of nerves in the shoulder. At present, sur­gical treatment is seldom indicated in cerebral and spinal palsy. With nerve palsies, however, surgery may be beneficial, but should be delayed until it is certain that maximal nonoperative im­provement has occurred.

Other Diseases of the Nervous System

There is a host of diseases of the nervous system which do not fall into specific classifica­tions, some of which for completeness may be mentioned here. It would appear that any part or combination of parts of the nervous system may become involved with disease of every nature and in conjunction with diseases of every other sys­tem. Many of these are very specific, but some are extremely vague. The etiology (cause) of most is known but still undetermined in many. Some are curable, while others can only be palliated. A few diseases of the nervous system have a very specific symptom complex, i.e., com­bination of symptoms always occurring together, called syndromes; usually the name of the syn­drome is derived from the name of the investiga­tor who first described it. Few have surgical import today.

Neuralgia is a term which literally means nerve-pain. It is applied to those conditions where the pain is thought to stem from a dis­order intrinsic to a nerve, whether or not the cause is apparent. The name neuritis is also applied to similar types of pain, even though the name implies inflammation which may not be present.

Whenever a muscle does not have proper nerve supply, it cannot contract normally. This is called paralysis; the muscle is weak and flabby. Excessive nerve impulses to a muscle cause spastic paralysis; the muscle or group of muscles remains tight in constant contraction. The terms palsy and paresis apply to conditions of flaccid paralysis, where there is weakness of the muscles from inadequate nerve supply.

With complete lack of nerve supply there is complete paralysis. The muscle which is not used degenerates and shrinks in size, to which the term muscular atrophy (no growth) is ap­plied.

Trigeminal neuralgia (tic douloureux) is a disease of the Vth cranial nerve. It is of unknown cause and is characterized by attacks of inter­mittent sharp shooting pains on the side of the face, teeth, or eyes. In mild cases medications may be of some help, but usually surgical pro­cedures eventually have to be employed. These include nerve injections, nerve section, neurec­tomy, trigeminal tractotomy by craniectomy, rhizotomy by craniectomy, high neck laminec­tomy, or ganglionectomy.

Meniere’s syndrome is a condition affecting the VUIth cranial nerve in which there is dizziness and progressive hearing loss. Treatment is most often medical, but surgical treatment by section­ing of the VUIth cranial nerve via craniotomy may be necessary.

Bell’s palsy is a paralysis of the muscles of one side of the face from involvement of the VI 1th cranial nerve. In some instances a cause may be ascertained, but in many it remains ob­scure. Sometimes it is associated with other dis­eases and subsides when the concurrent disease is cured. The affliction is often self-limited and subsides spontaneously, or with medical and/or electrotherapy means.

Erb’s palsy is a paralysis involving the shoul­der and arm from defective nerve supply at the shoulder (brachial plexus). It most often occurs from birth injury but may occur from injury at any age. When indicated, neurolysis may be performed. In the condition where there is an extra first rib, the so-called cervical rib, brachial plexus palsy may also occur; when the symptoms warrant, removal of such extra rib by surgery will give relief.

Muscular dystrophy is a disease character­ized by progressive weakness and wasting of the muscles. It is of unknown cause and no nervous system abnormality is apparent. However, it is possible with present research on this affliction that a defect of the nervous system will be found as the underlying cause.

Herniated intervertebral disc is a condition affecting the spinal cord. This is a disease in­volving both the skeletal and the nervous sys­tems and may be included in the study of either system. The intervertebral disc is a plate of cartilage which acts as a cushion between the vertebral bodies; it acts as a “shock absorber” with jarring injuries of the spinal column. This tough gristle-like substance is enclosed in a cap­sule. A rounded condensation in the center of the disc is called the nucleus pulposus. The disc may be injured in certain accidents, falls and lifting strains. In some cases the symptoms seem insignificant at first, but months or even years later, they may appear and be progressive. Then as the disc degenerates the capsule pushes back into the spinal canal against the dural lining to compress the cord or a spinal nerve as it emerges from the canal. This causes pain in the area of distribution of involved nerve or nerves.

Herniated nucleus pulposus has essentially the same symptoms and mechanism, but in this case the capsule ruptures and allows the nucleus to be pushed backward to protrude into the canal.

For all intensive purposes these two conditions are the same. In either case, continued pressure may produce degeneration of the involved nerves. Pain, changes in sensation, and loss of reflexes may occur. The area most often affected is the low back (low lumbar) region. Typically there is involvement of the sciatic nerve, for which symptoms the term sciatica is applied. X-ray studies, especially the myelogram, will demon­strate the area of pressure.

Treatment of this injury is at first conservative with each attack of symptoms. This includes traction on the legs or pelvis to attempt to relieve the pressure on the disc and relax the back mus­cles, physiotherapy, muscle relaxants, and pain remedies. Prevention of attacks may be accom­plished by close attention to the posture; sleep­ing, sitting, standing, and lifting postures are all important. Often back braces are employed to limit certain motions of the back which may aggravate the condition.

When conservative treatment fails to give permanent or complete relief, a more direct at­tack by operation may be indicated. Approach is made to the area of the protruding disc by laminectomy or hemilaminectomy. The entire disc or the fragments which protrude into the spinal canal are removed. Frequently an added stabilizing procedure is performed in the closure of the operation by placing a bone graft to fuse the spinous processes. This spinal fusion forms a bridge over the defective area to insure against recurrence of the protrusion. Diligent postoperative care over an adequate period of time is essential.

Hydrocephalus is a disparity in the forma­tion and absorption of the cerebrospinal fluid, or an obstruction of its circulation to its absorp­tion sites. In either case, the fluid is not absorbed as rapidly as it is formed. There results a disten­tion of the brain spaces, especially the ventricles, with progressive enlargement of the head. This occurs in infancy when the bones of the skull are not ossified (sealed together). At times the head may reach tremendous proportions, and the child usually dies in early life. Surgical treat­ment of hydrocephalus is by ventriculostomy, wherein the fluid is drained into another cavity.

Circulatory disturbances of the brain may be by one of several mechanisms. That of sudden onset is the so-called stroke, or cerebral vascu­lar accident (CVA). The brain requires a con­stant supply of oxygen; it can tolerate a lack of oxygenated blood supply for no longer than 3 minutes. Beyond this time death or idiocy will occur. The blood supply may be blocked by spasm of a cerebral vessel, cerebral spasm, which narrows its diameter and limits its flow. The blood flow may be blocked by clot which forms in a vessel, called cerebral thrombus. A blood clot from another site in the circulatory system which passes into a brain vessel to im­pede the flow is called cerebral embolus.

Bleeding in the skull from injury has been mentioned. The effects of compression of the brain by the collection of blood are the same in spontaneous cerebral hemorrhage. This type of stroke or CVA is caused by disease of the blood vessels. In arteriosclerosis (hardening of the arteries) and high blood pressure, a vessel may rupture to cause intracranial hemor­rhage. Most often there is little to be done sur­gically for this type hemorrhage, as the general condition and age of the patient will not tolerate extensive operative procedures.

Another type of spontaneous hemorrhage in the brain is from rupture of an aneurysm of one of the brain vessels. These are sac-like en­largements which have been present since birth, most often of the vessels at the base of the brain. Early operative intervention is essential and meets with a high degree of success.

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