Brain and spine arteriovenous malformations (AVMs) are abnormal tangles of blood vessels consisting of connections between the arteries and veins. They often do not cause any clinical problems until they rupture. AVMs can cause symptoms either by bleeding (rupturing), pressing on the brain or spinal cord, or by reducing the amount of oxygen reaching the brain tissue.
Symptoms might include the following:
Bleeding
Brain AVMs may cause bleeding into the brain (haemorrhage), causing sudden, severe headaches, confusion, nausea, vomiting, and may lead to a loss of consciousness.
Seizures
Seizures are a sudden, uncontrolled electrical disturbance in the brain that can cause changes in behavior, movements, feelings, and levels of consciousness. They can range in severity, from virtually undetectable periods of inattention or staring to full-blown convulsions.
Seizures can be categorized into focal (partial) and generalized (total) seizures:
Focal (Partial) Seizures: These seizures appear to result from abnormal activity in just one part of the brain. Focal seizures can occur without a loss of consciousness or with a change in consciousness. Symptoms might include sudden, jerky movements of one part of the body, distortions in hearing or seeing, stomach discomfort, or a sudden sense of fear. These seizures can also progress to a loss of consciousness and convulsions, a progression known as a focal-to-bilateral tonic-clonic seizure.
Generalized (Total) Seizures: These seizures involve all areas of the brain. They can cause a loss of consciousness, falls, muscle spasms, or convulsions. Generalized seizures are further categorized into several types including absence (formerly known as petit mal), tonic-clonic (formerly known as grand mal), atonic, and myoclonic seizures.
Convulsions refer to repeated, uncontrolled body movements. These are often seen in tonic-clonic seizures where the person may stiffen and have jerking muscle activity. The person may also lose consciousness. Finally, a person’s “level of consciousness” refers to their awareness of themselves and their environment. Changes in a person’s level of consciousness include being fully awake, responsive, unresponsive, or anything in between.
In the context of AVMs, these symptoms can result from the AVM disrupting the normal electrical activity of the brain.
Neurological Symptoms
These depend on the location of the AVM and can include muscle weakness or paralysis in one part of the body, a loss of coordination (ataxia) that can lead to such problems as gait disturbances, difficulties carrying out tasks that require planning, memory deficits, dizziness, visual disturbances such as a loss of part of the visual field, difficulties with speech (dysarthria), and abnormal sensations such as numbness, tingling, or spontaneous pain (paresthesia or dysesthesia).