Cerebral arteriosclerosis is not always of syphilitic origin, though probably much more frequently so than would be indicated by clinical statistics.

Disease of the arteries of the brain is often found at autopsies in cases which have shown during life no mental or nervous disturbances. The occurrence of such disturbances is probably determined by a certain extent or degree of arterial disease. Arteriosclerotic brain disease is but a part of general arteriosclerosis, though not infrequently the process is found to be much more marked in the brain than elsewhere.

The symptoms vary widely in different cases, depending chiefly upon the vessel or system of vessels affected.

Fig. 3 is a diagram of the arterial supply of the brain showing the circle of Willis, its branches and their distribution.

The terminal arterioles form two distinct systems: a system of short vessels supplying the cortex, and a system of long vessels which penetrate deeper and supply the marrow; the ganglionic vessels at the base constitute a part of the medullary system. The manner of distribution of the terminal arterioles is shown in Fig. 4.

1 Binswanger. Berlin, klin. Wochenschr., 1894. - Alzheimer. Allg. Zeitschr. f. Psychiatrie, 1902. - Gowers. Manual of Diseases of the Nervous System. - Lambert. N. Y. State Hosp. Bulletin, Vol. I; also in 20th Ann. Report N. Y. State Commission in Lunacy, pp. 91 et seq.

Arterial Supply of the Brain

Fig. 3. - Arterial Supply of the Brain.

Arteriosclerotic disease may affect chiefly the large vessels given off from the circle of Willis or their principal branches; or it may affect chiefly the terminal arterioles, either the cortical or the medullary system, though the process is hardly ever sharply limited to any one system of vessels.

Long or Medullary Arteries

Fig. 4. - 1. Long or Medullary Arteries. 2. Short or Cortical Arteries. (After Charcot, from Gray's Anatomy.)

The manner in which the nervous tissues are affected is variable. Narrowing of the lumen of a vessel resulting from obliterative endarteritis brings about atrophy of the nervous elements, due to reduction of the blood supply, there being at the same time hypertrophy of the neuroglia tissue ("perivascular gliosis" of Alzheimer); thickening of the walls of the smallest arterioles and of the capillaries ("arterio-capillary fibrosis") results in atrophy through interference with osmotic processes; roughening of the in-timal lining of the vessels results in the formation of thrombi or emboli with consequent infarction and softening; the brittle and weakened condition of the vessel walls and aneurismal dilatations combined with general rise of blood pressure result in rupture and hemorrhage with compression and destruction of nerve tissue to an extent depending upon the amount of extravasated blood.

The symptoms of arteriosclerotic brain disease may perhaps be most conveniently classified as follows: (1) systemic symptoms; (2) symptoms common to all forms of arteriosclerotic brain disease; (3) symptoms of occlusion of large vessels or their branches; (4) symptoms of affection of the medullary system of terminal arterioles; (5) symptoms of affection of the cortical system of terminal arterioles.

(1) Systemic Symptoms. These will not be dwelt upon in detail here, as they are more properly a subject of textbooks of general medicine. As being among the most important may be mentioned: rigid and tortuous peripheral arteries, increased blood pressure, pulse high in tension but small in volume, increased area of cardiac dullness, accentuation of the aortic sound, often evidences of chronic interstitial nephritis.

(2) Symptoms Common to all Forms of Arteriosclerotic Brain Disease, (a) Physical symptoms: headache, insomnia, muscular weakness, imperfect muscular control, attacks of faintness or dizziness, epileptiform or apoplectiform seizures. (b) Mental symptoms: diminished capacity for work, undue fatigability, emotional instability, states of depression or anxiety, drowsiness; later forgetfulness, disorientation, and general mental deterioration; a characteristic feature is the persistence of insight for a long time.

(3) Symptoms of Occlusion of Large Vessels or Their Branches. The symptoms usually come on suddenly in the form of a stroke, often, but by no means always, accompanied by loss of consciousness lasting from a few minutes to several hours or even longer; this may be followed by a dazed, confused, or delirious period from which the patient recovers with permanent symptoms the character of which depends upon the location and extent of the lesion.

(a) Occlusion of the anterior cerebral artery is uncommon; the symptoms depend upon the point of occlusion and upon whether the main vessel or one of its branches is occluded; there may be no special symptoms, or there may be loss of the sense of smell on one side or crural monoplegia.

(6) Occlusion of the middle cerebral artery or of its branches is very common; the characteristic symptoms for the four branches respectively are: (a) motor aphasia; (β) facial or brachial paralysis, or both; (7) astereognosis; (δ) partial bilateral deafness, sensory aphasia, possibly lower quadrant hemianopsia. Lesions of the right hemisphere produce no aphasia in right-handed persons.

(c) Occlusion of the posterior cerebral artery has for its special symptom hemianopsia; this symptom, however, occurs only when either the main vessel or its occipital branch is affected.

(d) The cerebellar arteries communicate with each other by fairly free anastomosis; for that reason occlusion of one of them may cause but slight damage and give rise to no permanent symptoms; when the area of softening is extensive there are apt to be vomiting, vertigo, and muscular incoordination. In some cases the lesion involves parts of the pons and medulla, causing crossed hemiansesthesia, loss of the sense of taste, dysphagia, and aphonia, and rapidly leading to a fatal termination.

Occlusion of these vessels does not in itself as a rule cause marked general mental deterioration aside from that which is the characteristic accompaniment of states of aphasia.

(4) Disease of the Medullary System of Terminal Arterioles ("chronic subcortical encephalitis" of Binswanger) presents a characteristic picture at autopsy: the brain shows more or less pronounced atrophy which is general but which is apt to be more marked in irregular foci; the surface of the brain is smooth, the cortex, though possibly somewhat thinned, is otherwise normal in gross appearance; the white substance and often the basal ganglia present on section slit-like defects where the nerve substance has disappeared either by gradual atrophy or through sudden infarction; these defects may be so numerous that the brain substance, riddled with them, presents a spongy appearance which has been called etat crible; in other cases there may be but one or two of them in each hemisphere. The distribution of the affection is variable; usually it is bilateral; in some cases, however, it may involve largely one hemisphere, the other being almost entirely spared; in other cases the ganglionic vessels are the principal seat of the affection.

The more striking clinical features of this type of cerebral arteriosclerosis are recurrent epileptiform or apoplectiform seizures and paralyses, anaesthesias, and mental deterioration the course of which is irregularly progressive, increasing with each seizure and remaining stationary or even receding somewhat in the intervals; toward the last the patients become helpless owing to paralyses, contractures, and profound dementia.

In cases in which the affection is largely confined to the ganglionic vessels the dementia is but slight. In such cases there is a special tendency toward the formation of small aneurisms which frequently burst, and the resulting hemorrhage into the basal nuclei, the internal capsule, and the lateral ventricle gives rise to the familiar clinical picture of cerebral apoplexy followed by hemiplegia, dysarthria, etc.

(5) Disease of the Cortical System of Terminal Arterioles also presents a characteristic anatomical picture. The surface of the cortex instead of being smooth is irregularly pitted with small depressions which mark the sites of atrophy and contraction in the regions supplied by the cortical arterioles the lumina of which have become narrowed or completely obstructed. The lesion is as a rule unequally distributed but rather extensive, so that there is marked general brain atrophy. Microscopically one finds various stages of chronic nerve cell change: pigmentary degeneration shrinkage, atrophy; the nervous elements in the affected areas ultimately disappear and are replaced by glia tissue.

Clinically the special feature here consists in various irritative phenomena followed later by loss of function: tremors, athetoid or choreiform movements, various seizures, paresthesias, and later paralyses and anaesthesias. The mental symptoms are apt to be prominent from the beginning: hallucinations, agitation, violent excitement, confusion, inaccessibility.

Diagnosis

General paralysis may be closely simulated but can always be excluded with the aid of lumbar puncture which in cerebral arteriosclerosis regularly gives negative results.

Acute syphilitic endarteritis affecting the brain arteries may be clinically indistinguishable from cerebral arteriosclerosis. The differentiation may be made with the aid of the Wassermann reaction. Cases of arteriosclerotic brain disease, even when due to old syphilitic infection, usually give a negative reaction, for in such cases as a rule the syphilitic process is no longer active, the lesions being postsyphilitic.

The differentiation from senile dementia may be difficult especially when the latter is complicated by more or less marked arteriosclerosis, as is so often the case. It must be borne in mind that senile dementia has for its basis a process of atrophy which is wholly independent of vascular disease. Focal symptoms, recurrent seizures, persisting mental insight, also stationary condition and duration over five years, all point to cerebral arteriosclerosis. Senile dementia is but exceptional before the age of sixty years, while cerebral arteriosclerosis often begins at fifty or even earlier.

The course of cerebral arteriosclerosis in most cases extends over a number of years, even ten or twenty years. It is irregularly progressive, as already described. In any case sudden death may occur from embolism, apoplexy, or from exhaustion following convulsions. Kraepelin speaks of a grave progressive form which is characterized by rapid development of extreme dementia and an early fatal termination.

The prognosis of all forms of arteriosclerotic brain disease is unfavorable for recovery from established defect symptoms; sudden or gradual progress of the disease is to be expected to occur sooner or later, though the condition may remain approximately stationary for months or even years, expecially under favorable conditions.

The treatment is purely symptomatic. Rest, freedom from worry or excitement, moderation in eating and drinking, abstinence from alcohol, proper regulation of the bowels may stave off progress of the disease or the occurrence of seizures.