COMBINED SYSTEM DISEASES. 105 (c) of the Entire Pathway.-In these cases there is degeneration of the pyramidal tract and of the peripheral nerves (ganglion cells and fiber, peripheral nerve)—that is, amyotrophic lateral sclerosis and possibly bulbar paralysis. The clinical symptoms are those of spastic paralysis of the extremities, with degenerative muscular atrophy. It is probable that numerous intermediate forms between these distinct varieties occur. 2. System Diseases of the Centripetal Sensory Path. We do not know of any isolated affections of the central path belonging to this category. There is, however, a degeneration of the peripheral neuron (so-called tabes dorsalis) of quite frequent occurrence, in which the neuron may be affected in its entire extent. In rare cases the central pathway may also be involved (lateral cerebral and anterolateral tract). The symptoms consist in painful sensations and disturbances of sensation and coordination; the reflexes are abolished. This category also includes the sensory form of multiple neuritis. 3. The Combined System Diseases.-These include degenerative processes affecting simultaneously both the motor and the sensory paths. (a) Hereditary or Friedreich's Ataxia.-The central motor neuron (pyramidal tract) and the peripheral and central sensory neuron (posterior columns, cerebral lateral tracts) are diseased. (For symptoms see Special Pathology.) (b) Tabes combiné, or true tabes, with participation of the lateral pyramidal tracts, frequently with participation of other neurons-for instance, peripheral motor neurons (oculomotor, abducens, etc.). (c) Another class of morbid diseases, better known anatomically than clinically (posterior columns, lateral cerebellar tract, pyramidal tract). Whether other cerebral tracts may become the primary seat of system disease is not known. 4. General Considerations on Methods of Examination and Diagnosis. 1. Before proceeding with the examination, the history should be carefully taken, as it is often of the greatest assistance in the diagnosis. Among others, the following points should be carefully determined : (a) Heredity (nervous diseases, consanguinity of the parents, psychosis, alcoholism, suicide, tuberculosis, and syphilis). (b) The previous history of the patient in regard to mode of life and habits (education, temperament, alcohol, tobacco, morphin, excesses of every kind); occupation (overexertion, manual work, lead, arsenic); former diseases (psychic and bodily injuries, acute infectious diseases, tuberculosis, and syphilis). (e) The history of the present disease, its cause, mode of origin, and course. 2. The examination of the nervous system should in every instance be preceded by a careful examination of the general condition and of the state of the more important internal organs (nutrition and vigor, lung, heart, abdominal functions, pulse, urine). Particular attention should be paid to symptoms of syphilis, tuberculosis, purulent foci, malignant tumors, bone diseases, diabetes, aural and ocular diseases. I. The Examination of the Motor Sphere. This includes: 1. The external condition of the muscles (atrophy, hypertrophy, folds in the muscles), to determine which, by inspection, the examiner's eye must be trained by constant study of the normal body. Atrophy in the muscles of the hand, peroneal atrophy, facial paralysis, atrophy of the shoulder-girdle, abnormal position of the extremities, etc., can be seen at the first glance. This part of the examination should include measurement EXAMINATION OF THE MOTOR SPHERE. 107 of the atrophied extremities with a tape-measure and comparison with the sound side. 2. Examination for Motor Irritative Symptoms.These include tremors of the extremities (alcoholism, morphinism, neurasthenia, Basedow's disease); we distinguish fine tremors, up to twenty a second, and slow tremors, up to six vibrations a second. Special forms are the tremor of paralysis agitans, the intention tremor in multiple sclerosis, which is rather a disturbance of coordination, and nystagmus of the eye muscles. Spasms of individual muscles or muscle groups, either clonic (interrupted) or tonic (uninterrupted), and tetanoid or tonic spasm of all the muscles of the body. A contracture is a permanent tonic condition of spasm. A convulsion is a form of extensive tonic or clonic spasm; epileptiform convulsions are periodic convulsions (also hysteric convulsions). Choreic movements are involuntary, but not brusque, like true convulsions; the movements are irregular and occur in the quiescent state. Athetoid movements are similar, but extraordinarily exaggerated movements, occurring especially in the fingers and toes. These conditions may be present in cortical lesions or after apoplexies, but may also occur without apparent cause. Fibrillary muscular contractions have been referred to on page 83. 3. The Examination of Motor Power.-The power of each of the more important muscles should be tested separately. For estimating the power of some of the muscles, as those used in gripping, we have the dynamometer, but in most cases the strength of the muscle is determined by comparing it with that of the other side and by the resistance offered to the hand of the examiner. Proficiency in this respect can only be acquired by long practice. The functions of all the muscles are tested in the order of the motor nerves, beginning with the eye muscles. (See Plate 27.) The extent and force of both active and pas sive movements should be determined, the attention being specially directed to the joints. It is exceedingly important to examine the gait : whether it is paretic or laborious, as a result of muscular weakness; spastic, on account of abnormal muscular stiffness; ataxie, from disturbance of the coordination; hemiplegic, the patient dragging one of his legs and advancing the other by a movement of adduction instead of raising the foot (in central paralysis); or, finally, peroneal, the tips of the toes dragging on the ground because the peronei are paralyzed. 4. Examination of the Power of Coordination. This is done by requiring the patient to carry out complicated movements of the arms, such as bringing the tips of the fingers together, and various movements of the legs. If the nicety of the movements is impaired, the condition is termed ataxia. It occurs in multiple sclerosis, tabes dorsalis, hereditary ataxia, multiple neuritis, etc. Static coordination (attitude of the trunk) is tested by requiring the patient to stand with his eyes closed; swaying under these conditions is known as Romberg's sign. In cerebellar ataxia the gait resembles that of a drunken man and is very characteristic. 5. Examination of the Electric Condition of the Muscles. Electric Diagnosis. This is a diagnostic procedure of the greatest value. In the electric examination we utilize the galvanic, primary, or constant current; or the faradic, induced, secondary, or interrupted current. galvanie is the more important. The (a) Galvanic Examination.-The usual apparatus con tains: J Zine in HSO4. Leclanché's cell Carbon (Braunstein) in HCL. Zine in KMnO, H2SO1, ELECTRIC DIAGNOSIS. 109 with the addition of sulphid of mercury to replace the used-up zinc amalgam. The chemic processes (formation of a salt) that are set up in these cells produce a difference in the electric. potential between the two poles, the zinc pole (negative pole, oxygen pole) and the carbon pole (positive pole, hydrogen pole), and the neutralization of this difference by wire connections produces the galvanic electric current. The current flows from the positive pole (anode) to the negative pole (cathode)-that is to say, from the carbon to the zinc. To assist the memory it may be remembered that C comes before Z. The electromotive force depends on two conditions: the internal resistance offered by the cells and the external resistance that the current has to overcome. The dry skin of a human being at first offers a very great resistance when it is included in the circuit. After a time the resistance diminishes and is finally overcome, the current passing without interruption. The strength of the current is measured by means of the galvanometer, and is expressed in milliamperes, an arbitrary unit which has now come into general use. The strength of the current can be graduated by means of rheostats (the addition of resistance coils). The healthy muscle, when irritated with the galvanie current, reacts with a rapid and lightning-like contraction, both on opening and closing the current, the contractions taking place in the following order as the strength of the current is increased : On cathodal closing, CCI; anodal closing, AC1; anodal opening, AO; and, finally, on cathodal opening, CO. If the current is still further increased, a tetanic contraction takes place (CCITe before ACITe). When the muscle is degenerating the electric reactions are somewhat different. The contraction does not take place abruptly and like a flash of lightning, but slowly, sluggishly, and in distinct, visible waves. In addition, anodal closing contraction takes place before the cathodal |