Injury Clinic

Former USC DL Mike Patterson has AVM

By Paragon SC Aug 4, 2011, 2:26pm PDT

We all heard the terrible news about Mike Patterson having a seizure on the practice field yesterday.

We now know what caused this.

A brain AVM (arteriovenous malformation) is an abnormal connection between arteries and veins. An AVM is typically congenital, meaning it dates to birth. An AVM can develop anywhere in your body but occurs most often in the brain or spine. A brain AVM, which appears as a tangle of abnormal arteries and veins, can occur in any part of your brain. The cause isn't clear.

You may not know you have a brain AVM until you experience symptoms, such as headaches or a seizure. In serious cases, the blood vessels rupture, causing bleeding in the brain (hemorrhage). Once diagnosed, a brain AVM can often be treated successfully.

These are the potential complications of AVM

Complications of a brain AVM include:

Bleeding in the brain (hemorrhage). Walls of the affected arteries and veins may become thin or weak. An AVM puts extreme pressure on these walls, since no capillaries are available to slow down the blood flow. A hemorrhage may result. A very small (microscopic) hemorrhage causes limited damage to surrounding tissues and is unlikely to produce noticeable symptoms. A larger hemorrhage, however, can cause brain damage and is known as an intracerebral hemorrhage when bleeding occurs in the brain tissue.

Reduced oxygen to brain tissue. With an AVM, blood bypasses the network of capillaries and flows directly from arteries to veins. Blood rushes quickly through the altered path because it isn't slowed down by channels of smaller blood vessels. Surrounding brain tissues can't easily absorb oxygen from the fast-flowing blood. Without enough oxygen, brain tissues weaken or may die off completely. This results in stroke-like symptoms, such as difficulty speaking, weakness, numbness, vision loss or severe unsteadiness.

Thin or weak blood vessels. An AVM puts extreme pressure on the thin and weak walls of the blood vessels. A bulge in a blood vessel wall (aneurysm) may develop and become susceptible to rupture.

Brain damage. As you grow, more arteries may be "recruited" to supply blood to the fast-flowing AVM. As a result, some AVMs enlarge, which displaces or compresses portions of the brain. This may prevent protective fluids from flowing freely around the hemispheres of the brain. If fluid builds up, it can push brain tissue up against the skull — a condition known as hydrocephalus.

Depending on how sever Patterson's condition is will determine his future in the NFL.

Good stuff after the jump...

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Image courtesy of the Mayo Clinic

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Image Courtesy of The NIH

I would suspect that Patterson is done for the year...and maybe for his career. But it is also entirely possible that he could be back next season once he has completed all of his treatment and rehab.

Here are the symptoms.

Signs and symptoms of a brain AVM include:

Seizures

A whooshing sound (bruit) that can be heard on examination of the skull with a stethoscope or may be audible if you have an AVM

Headache

Progressive weakness or numbness

When bleeding into the brain occurs, signs and symptoms can be similar to a stroke and may include:

Sudden, severe headache

Weakness, numbness or paralysis

Vision loss

Difficulty speaking

Inability to understand others

Severe unsteadiness

Symptoms may begin at any age, but you're more likely to experience symptoms before age 50. Brain AVM can damage brain tissue over time. The effects slowly build up, sometimes causing symptoms in early adulthood. Once you reach middle age, however, brain AVMs tend to remain stable and are less likely to cause symptoms.

It will be interesting to know if Patterson experienced any of these symptoms.

So often we ignore some of these symptoms, unless they are frequent and severe. Patterson is in pretty good physical shape so because this is a congenital condition he probably shrugged off any of the above listed symptoms.

Treatment.

There are several potential treatment options for brain AVM, and the best treatment depends on the size and location of the abnormal blood vessels. Medications may also be used to treat related symptoms, such as headaches or seizures.

Surgical removal (resection). Surgical treatment of a small brain AVM is relatively safe and effective. A section of skull is removed temporarily to gain access to the AVM. The neurosurgeon, aided by a high-powered microscope, seals off the AVM with special clips and carefully removes it from surrounding brain tissue. The skull bone is then reattached, and the scalp is closed with stitches.

Resection is usually done when the AVM can be removed with acceptable risk to prevent hemorrhage or seizures. AVMs that are in deep brain regions carry a higher risk of complications. In these cases, other treatments may be considered.

Endovascular embolization. During this procedure, a long, thin tube called a catheter is inserted into a leg artery and threaded through the body to the brain arteries. The catheter is positioned in one of the feeding arteries to the AVM, and small particles of a glue-like substance are injected to block the vessel and reduce blood flow into the AVM.

Endovascular embolization may be done alone, before other treatments to reduce the size of the AVM, or before surgery to reduce the chance of bleeding during the operation. In some large brain AVMs, endovascular embolization may reduce stroke-like symptoms by redirecting blood back to normal brain tissue.

Stereotactic radiosurgery. This treatment uses precisely focused radiation to destroy the AVM. The radiation causes the AVM vessels to slowly clot off in the months or years following the treatment. This treatment works best for small AVMs and for those that have not caused a life-threatening hemorrhage.