A thrombosis is the formation, development, or existence of a blood clot. In this diagnostic code, the clot is in a brain blood vessel, which leads to cerebral infarction. The location may be anywhere in the arterial tree, and may stop the blood supply to an area of the brain causing ischemia.

Etiologic factors related to the development of this condition may include: vasculitis; atherosclerosis; arterial dissection or hypercoagulable states.

In general, signs and symptoms of this condition will depend on the area of the brain that becomes ischemic. Signs and symptoms of a carotid artery obstruction may include blindness, paralysis, and aphasia. An embolism of the vertebrobasilar system may be characterized by confusion; vertigo; blindness; slurred speech; diplopia; dysphagia, unsteady gait and tingling of extremities.

Diagnostic measures may include: magnetic resonance imaging (MRI); computed tomography (CT) scan or ultrasonography; and cerebral arteriogram. Other diagnostic measures may include: lumbar puncture; ophthalmoscopy; electrocardiogram (EKG); electroencephalogram (EEG); complete blood count (CBC); coagulation tests and urinalysis.

Treatment may include: antiplatelet agents; anticoagulants; and, for some, vascular surgery may be indicated.

The extent of the brain affected by ischemia and the immediacy of treatment will determine the outcome. Visual disturbances, paralysis, aphasia, diplopia, dysarthria, numbness, and unsteady gait may persist, and, as a result, rehabilitation measures and physical therapy would be required.

• In those cases where there is severe neurologic deficit, consider entitlement under 38 CFR 3.350 [Special monthly compensation ratings]; competency under 38 CFR 3.353 [Determinations of incompetency and competency]; and ancillary benefits under 38 CFR 3.807, 38 CFR 3.808 [Automobiles or other conveyances; certification], 38 CFR 3.809 [Specially adapted housing], and 38 CFR 3.809a [Special home adaptation grants].

• This disease shall be granted service connection although not otherwise established as incurred in or aggravated by service if manifested to a compensable degree within the applicable time limits under 38 CFR 3.307 following service in a period of war or following peacetime service on or after January 1, 1947, provided the rebuttable presumption provisions of 38 CFR 3.307 are also satisfied [38 CFR 3.309 [Disease subject to presumptive service connection], 38 CFR 3.309(a) [chronic disease].

• It is required for the minimum ratings for residuals under diagnostic codes 8000-8025, that there be ascertainable residuals. Determinations as to the presence of residuals not capable of objective verification, i.e., headaches, dizziness, fatigability, must be approached on the basis of the diagnosis recorded; subjective residuals will be accepted when consistent with the disease and not more likely attributable to other disease or no disease. It is of exceptional importance that when ratings in excess of the prescribed minimum ratings are assigned, the diagnostic codes utilized as bases of evaluation be cited, in addition to the codes identifying the diagnoses.

• Disability in this field is ordinarily to be rated in proportion to the impairment of motor, sensory or mental function. Consider especially psychotic manifestations, complete or partial loss of use of one or more extremities, speech disturbances, impairment of vision, disturbances of gait, tremors, visceral manifestations, injury to the skull, etc. In rating disability from the conditions in the preceding sentence refer to the appropriate schedule. In rating peripheral nerve injuries and their residuals, attention should be given to the site and character of the injury, the relative impairment in motor function, trophic changes, or sensory disturbances.  38 CFR 4.120

• With the exceptions noted, disability from the following diseases and their residuals may be rated from 10 percent to 100 percent in proportion to the impairment of motor, sensory, or mental function. Consider especially psychotic manifestations, complete or partial loss of use of one or more extremities, speech disturbances, impairment of vision, disturbances of gait, tremors, visceral manifestations, etc., referring to the appropriate bodily system of the schedule. With partial loss of use of one or more extremities from neurological lesions, rate by comparison with the mild, moderate, severe, or complete paralysis of peripheral nerves” 38 CFR 4.124a