Brown-Sequard Syndrome: Hemisection of the Cord

Brown-Sequard syndromeBrown-Sequard Syndrome

Injury to half the spinal cord, or “hemisection of the cord,” can occur with trauma, tumor, or disc herniation. But most often it is seen in textbooks and in med school exams! The injury produces a unique constellation of findings: loss of motor and fine touch on the same side as the injury, and loss of pain/temperature on the opposite side. This is the Brown-Sequard syndrome.

Here’s how it happens.

First to orient you to the cartoons. We all know what this is.

The Brain, actually!

The brain, actually!

And now the brain with the brainstem and spinal cord.

Brain, brainstem, spinal cord

Of all the tracts in the spinal cord, there are really only three you need to know to get started. There is one efferent pathway, the corticospinal tract that carries motor signals from the brain to the body. There are two afferent pathways that carry sensory information to the brain, the dorsal columns which carry proprioception and fine touch, and the spinothalamic tract which transmits pain and temperature.

Note the location of the “crossover” of these tracts. This crossover point is the key to understanding the clinical features of the Brown-Sequard syndrome. The corticospinal tract and the dorsal columns cross over in the medulla, at the “decussation of pyramids.”

Corticospinal tract

Dorsal columns

By contrast, the spinothalamic tract doesn’t cross to the opposite side until it exits from the cord.

Spinothalamic tract

So what if you have an injury to the left side of the cord. What will be the expected clinical findings? What neuro deficits will result?

Left hemisection of the cord

This is the Brown-Sequard syndrome. Loss of motor and fine touch ipsilateral to the lesion, and contralateral loss of pain and temperature.Ipsilateral loss of motor and fine touch

Advertisements

Subdural Hematoma: When to Cut

Subdural Hematoma: When to Cut

Subdural hematoma is a common neurosurgical problem. A subdural usually occurs in patients with significant brain atrophy, such as the elderly or alcoholic. Even minor trauma can injure the bridging veins between the brain and the dura. Bleeding into the subdural space can occur rapidly, causing death in a matter of hours, or gradually over a period of weeks. The surgical management depends on whether the hemorrhage is acute or chronic.

Acute Subdural Hematoma

An acute subdural may result from trauma or in a patient on antiplatelet or anticoagulant drugs. Symptoms often include headache, hemiparesis or alteration of consciousness like agitation, lethargy, or coma. If the acute subdural is small, it can be managed non-surgically. Antiplatelet drugs are stopped, and coagulation is corrected. Careful clinical observation is imperative. The subdural may expand as it becomes chronic, as the osmotic effect of the blood products draws free CSF into the subdural space. All this to say, if a small, acute subdural isn’t surgical today, it may be in two weeks!

Here a moderate sized, acute subdural is seen. You will notice a hyperdense (white) mass over the cortical surface of the brain (arrow), with effacement of the gyral pattern adjacent to the subdural, along with asymmetry of the lateral ventricles and midline shift.

Acute subdural hematoma

This patient was taken to surgery for a craniotomy. In the craniotomy, a large section of the skull was removed. This is called “turning a flap.” It allows the evacuation of the blood clot. At surgery, the clot was so tenacious it could be picked up with forceps. This, by the way, is the reason that an acute subdural cannot be drained with a bur hole. The blood is congealed. It cannot be drained with a bur hole any more than a cup of Jello can be eaten with a straw: it is solid. Air is introduced into the head at the time of surgery. It appears jet black on CT (arrow).

Acute subdural hematoma post op

Chronic Subdural Hematoma

On CT, a chronic subdural is hypodense (dark). It represents old blood in a liquid state. How old is old? It takes about two weeks for an acute subdural to liquefy, and the CT appearance will evolve from hyperdense to hypodense as the hemorrhage becomes chronic. Symptoms include headache on the same side as the subdural. Hemiparesis may be mild or well compensated as weakness occurs gradually. Many patients experience hemiparesis as gait imbalance, or veering to one side. As the patient worsens, frank lethargy or coma may ensue.

Here is a chronic, subacute subdural hematoma. You see a hypodensity over the cerebral convexity anteriorly (double arrow), with a hyperdense component posteriorly (arrow). There is effacement of the gyral pattern, ventricular asymmetry and midline shift.

Subacute chronic subdural hematomaChronic subacute subdural hematoma with labels

This patient was taken to the operating room for bur-hole evacuation of the subdural. The liquefied blood was removed with a simple bur hole. Going back to the Jello analogy: If you leave Jello at room temperature, it turns to liquid; in this case you CAN drink it with a straw. Or drain a chronic subdural with a bur hole!

Here you can see postoperative air in the head (jet black, see arrow), with a mix of residual chronic and subacute blood, with improved mass effect. A drain is present (double arrow).

Chronic subdural hematoma post opChronic subdural hematoma post op with labels

To summarize, an acute subdural is a life threatening emergency, often requiring craniotomy within hours. The chronic subdural can be life threatening as well, but over a period of weeks, often treated with simple bur hole drainage.