CHAPTER XXVII

THE NERVOUS SYSTEM; NEUROLOGICAL MEMORANDA ·

SYNOPSIS: Remarks on the Clinical Pathology of the Nervous System.-Remarks on the Application of Electricity. Examination Scheme in Nervous Derangements.-Neuralgias.-Disturbances with Predominating Undue Motion.-Disturbances with Loss of the Power of Motion Predominating.-Disturbances with Loss of Consciousness Predominating-Derangements with Psychical Alterations Predominating.—Vasomotor and Trophic Disturbances.-Meningitis in Adults.-Syphilis of the Nervous System.-Miscellaneous Lesions of the Brain and Cord with Pressure Symptoms, in which Localization and Surgical Aid are Possible.- Remarks on the Sympathetic Nervous System.-Anatomical and Physiological Anomalies.

REMARKS ON THE CLINICAL PATHOLOGY OF THE

NERVOUS SYSTEM

THE nervous system stands at the head of psychic and bodily phenomena. When the entire nervous system is disturbed there are general symptoms. When the integrity of individual nerves and ganglia is disturbed there are localized symptoms, as shown in the various motor, sensory, secretory, reflex, trophic, electrical, and circulatory phenomena. The pathology of the central nervous system embraces congenital malformations, injury, compression, and circulatory disturbances (such as anæmia, hyperæmia, hæmorrhage, embolism, and thrombosis), acute inflammation, softening, sclerosis, chronic inflammation, syphilis, tuberculosis, carcinosis, parasitic invasion, cavity formation, etc. The lesion may be unilateral, bilateral, or in disseminated plaques. In a broad sense the integrity of the central nervous system depends largely upon a good circulation, provided that the blood contains normal ingredients.

The cerebrospinal nervous system is practically made up of various types of neurones.

There are neurones transmitting nerve energy from the periphery of the body to the central nervous system. These are called centripetal neurones. The others carry the nerve impulse from the central nervous system to the periphery, and they are called centrifugal neurones. In the sensory system of neurones (centripetal neurones) there are usually three or four neurones; in the motor system (centrifugal) there are only two. Our knowl. edge of the sensory neurones is not complete, so that it is difficult in most cases to recognize by the symptoms, in a lesion of the sensory system, whether this lesion is in the first, second, third, or fourth sensory

neurone.

When there is a lesion of the motor system the conditions are different. Here we can definitely state by the symptoms whether the lesion involves

the central or peripheral motor neurones. If central, there is paralysis of muscles or spasticity of muscles. There is no trophic disturbance as a rule and no disturbance of electrical reaction. If peripheral, there are paralysis and trophic disturbance, such as atrophy of muscles, and disturbance of electrical reaction.

The white matter of the central nervous system carries or transmits impulses. The gray matter receives and transmits impulses and may store potential energy to transmit impulses. The gray matter of the basal ganglia is the centre for automatic action.

The gray matter of the spinal or medullary centre is the seat of reflex action. Each lower system is under constant control from above. The symptoms of a nerve lesion will be of a destructive or irritative nature, or show a combination of both.

A neurosis is a functional derangement of the nervous system, exclusive of mental derangement, which is called psychosis. Neuritis means nerve inflammation. Neuralgia means nerve pain.

Liquor Cerebrospinalis.-The brain and cord are surrounded by cerebrospinal fluid, which evidently acts as a buffer to lessen shock and injury. This fluid stands under a positive pressure and contains but little albumin. When pressure and tension increase by reason of inflammatory processes, tumors, etc., the choked disc of the optic nerve ranks first in diagnostic importance. When pressure increases to the extent of compression of blood vessels, we observe symptoms of direct pressure, such as vomiting, slow pulse and respiration, epileptoid convulsions, and coma.

Direct cerebral injuries, such as concussion of the brain or apoplexy, show the aforementioned respiratory and circulatory disturbances and generally a loss of pupillary reaction. Embolic processes in the brain show about the same symptoms as apoplectic cases.

MOTOR PHENOMENA

Complete motor inability is called paralysis. Incomplete motor inability is called paresis. We speak of ataxia, incoordination, and athetosis when there is an uncertainty of movements. The causative factors of such motor disturbances may be psychical or may be due to pressure (tumor, hæmorrhage); or they may be of inflammatory origin (infection by microorganisms or action of toxines); or they may be due to circulatory disturbances in the nerve centres. Motor disturbances may also be due to pathological lesions in the muscle proper. To the latter group belong the muscular dystrophies, muscular rheumatism, muscular trichiniasis, and parenchymatous degeneration of muscle.

Paralysis and Paresis

Paralysis is a loss of motor power more or less complete. It may be associated with sensory disturbances and with muscle atrophy and reflex disturbances.

There are four types, or classes: Monoplegia is a paralysis of one limb. Hemiplegia is a paralysis of one half of the body. Paraplegia is a paralysis. of the two lower limbs. Diplegia is a paralysis on both sides.

PARALYSIS DUE TO MUSCULAR DISEASE

677

Paralyses may be central as a result of brain lesion, as in hemiplegia, they may be due to cord lesions, or they may be peripheral, as from neuritis or disease of the muscles.

The cerebral type of paralysis is usually unilateral, involving the whole half of the opposite side of the body, including the lower half of the face (possibly with aphasia)

and deviation of the tongue to the paralyzed side. The muscle condition expresses itself usually by absence of atrophy or wasting. Another characteristic of brain palsy is the spasticity, or rigidity with exaggeration of reflexes. There is only a slight quantitative electrical change.

Spinal paralysis (when the peripheral motor neurone is involved) is characterized by a wasting of muscle and, except in myelitis, absence of sensory disturbance. We observe in spinal paralysis flaccidity instead of rigidity and a diminution or loss of reflexes and the reaction of degeneration.

Paralysis Due to Disease of the Nerves in the Course of Their Distribution. This form may be traumatic or toxic. The traumatic paralyses following dislocation, fracture, and pressure of any kind are generally local, and a return of electrical response, faradic and galvanic, indicates recovery of the nerve. The toxic

forms are generally bilateral, with a loss of reflexes and muscular excitability, such as in alcohol, arsenic, and lead neuritis, etc., and in paralysis following infectious diseases (the syphilitic form is irregular in distribution).

Paralysis Due to Muscular Disease. In this form the changes are in the muscles themselves, as in pseudohypertrophic paralysis and the scapulohumeral type of wasting. In these cases there is probably some congenital developmental defect. The electrical reaction is quantitatively reduced.

Paralysis and wasting of muscles associated with joint affections are of great practical importance. In rheumatoid arthritis there is a bilateral joint affection with enlargement of the bones, and the muscles become so atrophied that the patient resembles a skeleton.

The seat of the disturbance known as myotonia (Thomsen) and myasthenia gravis pseudoparalytica is not definitely known.

Finally, we note motor disturbances due to disease of the bones, tendons, and joints with intact muscles and intact nerve centres.

Disturbances of motor coordination, such as tabes dorsalis, are believed to be due to a lack of centripetal impulse and defective or increased reflexes from various organs of special sense. Incoordination may be of cerebral, cerebellar, or spinal origin.

Contractures (Active and Spastic).-Under certain conditions muscles for a time in a state of contracture will continue to be thus contracted and interfere with the free mobility of joints, and contrawise injury to, or lesion of, sensory nerves taking their origin in a joint, will produce contraction of muscles. Hysterical contractures are looked

upon as of psychic origin.

Neuropathic arthritis and osteitis, supposed to be due to analgesia and anesthesia, are observed in cases of tabes, syringomyelia, paralysis, apoplexy, and trauma.

Athetoid Movements; Athetosis.- Lesions in the motor tracts sometimes give rise to clonic spasms with slow, peculiar movements of the fingers and toes which are independent of voluntary action. They are a sequel of hemiplegia and may be mistaken for chorea in children.

Tremors are divided into those which occur during voluntary movements (intentional tremors), those which are constant, but increased by voluntary movements, such as tremors following acute infectious disease, and those which diminish after voluntary movements.

Choreic movements mean sudden jerking and incoordinate movements, forced movements, the patient being forced against his will to move in a certain direction. Associated Movements.-A movement in a non-paralyzed limb causes a movement on the affected side.

Convulsions, or spasms, are tonic or clonic in character. A tonic convulsion is a continuous contraction, as in tetany and tetanus. In clonic spasms contraction and relaxation of a muscle alternate rapidly, as in epileptic convulsions.

The symptoms, differential points, and management of a convulsive seizure are discussed in a separate chapter (see also Pædiatrics).

SENSORY, SECRETORY, AND SPECIAL SENSE PHENOMENA

679

SENSORY, SECRETORY, AND SPECIAL SENSE PHENOMENA Pain, hyperæsthesia, and paræsthesia are due to irritative lesions in the sensory tract. Destructive lesions of the sensory tract result in

1. Anæsthesia (hemianæsthesia), loss of tactile sensibility, which is tested by touching the part with a light object.

2. Analgesia, loss of sensibility to pain, which is tested by pricking the part with a pin. 3. Distorted temperature sense, which is tested by alternately touching the parts with a hot and a cold test tube.

4. Loss of muscle sense. This causes an ataxia, or an incoordination, in movements. Disturbances of localization are dependent upon the organs of special sense.

Secretory disturbances are manifested by an increase or diminution of glandular secretions.

Special Sense Symptoms. For symptoms referable to the sense of smell, see Rhinological memoranda.

For symptoms referable to the sense of taste, see Digestive disturbances.

For symptoms referable to the sense of sight and hearing and for pupillary phenomena, see Ophthalmic and Otic memoranda.

REFLEXES

FIG. 212. MUSCULAR DYS

TROPHY.

The disturbances of reflex action present very complicated conditions, and even in health there is a great difference in the intensity of reflex phenomena. Any irritation of superficial tissues will cause contraction of neighboring muscular elements, viz.: epigastric, cremasteric, plantar, conjunctival, pupillary, and palatal reflexes. They are distinguished as skin reflexes, deep reflexes (tendons and muscles), visceral reflexes (rectum, bladder, and genital apparatus), and organic reflexes (respiration, etc.).

The absence of cutaneous reflexes is not of much clinical significance. Examples of reflex activity are sneezing, winking, coughing, a flow of saliva or gastric juice, vomiting, and blushing. Without these life would cease. The skin reflexes are at present not well understood.

The deep tendon reflexes about the knee and ankle are generally present in health, and absence of the knee jerk generally denotes a lesion of the reflex arc. The author has met with individuals in good health with absent knee reflexes, and in some it is a family trait. Great care must be used in designating a reflex as diminished or exaggerated, because we have no reliable standard of what is normal. The light reflex should never be overlooked.

The so called organic reflexes preside over defæcation, urination, swallow