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


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.

When the Pain Is Worse than Films

When the Pain Is Worse than Films

Sometimes a patient will have excruciating pain, and rather bland films. Then your job is to make sense of the mismatch.

Secondary Gain

In some cases, “secondary gain” can motivate a patient to exaggerate their symptoms. The patient may receive compensatory pay for an injury that occurred while working. Maybe he or she gains sympathy from a significant other. I’ve seen cases where a passive spouse unconsciously employs a pain syndrome to get revenge on their abusive, controlling partner. The pain brings a benefit to the sufferer, and that benefit is the “secondary” gain.

However, secondary gain is always a diagnosis of exclusion. You may suspect it from the beginning, but in every case you are obligated to look for an underlying physiologic reason for the pain. Only after you have ruled out other causes of pain can you conclude the patient is seeking secondary gain.

Occult Fracture

She dove into water four feet deep, skinning her nose and chin. Stunned, she came back up to the surface complaining of terrible neck pain. Friends took her to the ER and this x-ray was obtained.

X-ray: Lateral C Spine

The plain X-ray looked normal

Her C spine was cleared and she was discharged. Over the next couple of days her neck pain persisted. Someone suggested chiropractic care, but first she sought the advice of a physician friend who recommended a CT scan. Here it is, showing a fracture of C7, with a traumatic subluxation of C7 on T1. Of great significance, the fracture was missed on the plain x-ray, which was technically perfect with visualization down to the C7-T1 disc.

CT C Spine Sagittal reconstruction


A 35 year old male with degenerative disc disease had been treated with some epidural steroid injections. Two injections gave partial relief for a couple of days, but within a month he worsened considerably. When we saw him, he was in severe pain, begging us for surgery. His MRI never looked that bad, and his worsening pain was curious to us. It didn’t all add up.Lumbar sagittal T1 without

So we sent him for another MRI without and with contrast, and blood work including CBC and Sed Rate. What was our suspicion? Infection or cancer. The pain was that bad. Sure enough, the MRI  showed enhancement about the L4-5 disc. It seems his run of the mill painful disc worsened due to an iatrogenic infection. Lumbar MRI T1 sagittal with contrastWe sent him for cultures and immediately started empiric antibiotics. He gradually improved over a full six weeks. No surgery was performed.

Spinal metastasis

If spine pain develops in someone with known, think spinal metastasis! The spinal pain of metastatic cancer is usually localized, without radicular or dermatomal radiation. It is worse at night while supine and better during the day. There may be dermatomal radiation if a spinal nerve is involved, or myelopathy if the cord is compressed. But usually the patient will complain of spine pain, worse at night. That alone is sufficient to warrant an MRI of the spine, without and with contrast, to evaluate spinal metastasis.MRI T spine without. Old T10 fracture

This 55 year old male had a T10 fracture a couple of years ago. He now presents with spine pain at night. MRI T spine is ordered, along with CT T spine. The cancers well known for metastasis to the spine are prostate, breast, and lung. Be on high alert in a patient with a history of cancer who now presents with new spinal pain.!MRI T spine. T1 with Contrast. Old fx T10. New cancer T12MRI T spine T1 with contrast. Old fx T10. New cancer T12CT axial shows invasion (lysis) of left T12 pedicle

The CT T spine confirms the lytic lesion of the left T12 pedicle, corresponding to the increased signal intensity on the MRI. The patient was sent for immediate radiation therapy for spinal metatstasis. He did not require surgery.

When pain exceeds imaging

When pain exceeds imaging, think FIRST –fracture–infection — cancer–as causes of spine pain. Check these out with MRI without and with contrast, CT, and even nuclear medicine bone scan. If, and only if, all these come back normal, then consider issues of malingering and secondary gain. But remember, your FIRST job is to find what others have missed or overlooked: occult fracture, infection, and cancer.

Books and other resources


Books and other resources

The learning curve is steepest at the beginning, and in neurosurgery you’ll never stop learning. I’ve received the greatest help from these:

Andrew H. Kaye, Essential Neurosurgery, 2005.Readable, simple overview of all the basics This is where you start. A very readable introduction to the brain and spine disorders and treatment, it is written on the level of the medical student or intern rotating on the neurosurgery service. 

Mark S. Greenberg, Handbook of Neurosurgery, 2010. A thousand-page “handbook” can be pretty intimidating, but it actually fits in your lab coat pocket.

It contains all the common neurosurgical problems you’ll have to manage, with plenty of cookbook formulas so you’ll know just what to order in patient care.

1000 pages of Awesome

Setti Rengachary, Principles of Neurosurgery, 2004. Far more emphasis on brain than spine, this one volume introduction is chock full of charts, diagrams and drawings to give you the big picture of neurosurgical problems. Concise, readable, relevant, this one is a real pleasure to read.One-volume textbook loaded with charts, diagrams

Daniel H. Kim, Surgical Anatomy and Techniques to the Spine, 2005. The pictures and diagrams are worth the price of the book, and in fact are included on a CD for handy electronic reference. I’ve even copied a page or two for patient education: “This is what will be done in your surgery.”Surgery in step-by-step drawings

And finally, just to keep you honest:

You don’t have to buy Duane E. Haines, Neuroanatomy An Atlas of Structures, Sections, and Systems, 2004. You lost me at hello. Sorry. It’s like  Netter’s Atlas on steroids: just too many named structures for a beginner. And that’s what this list is about.

Lumbar MRI: systematic reading

Lumbar MRI: a systematic reading

Alignment – Vertebrae – Conus – Cauda – Disc – Foramen

The most common pitfall in reading a lumbar MRI is focusing on the most obvious abnormality. It’s easy to do: your eye naturally goes to the vertebral slip, or the huge herniated disc. That’s natural, but in every case also be sure to do a systematic reading of the entire study. You’ll save yourself the pain and liability of missing a significant “incidental” finding.

So how to read the lumbar MRI systematically? Alignment – Vertebrae – Conus – Cauda – Disc – Foramen

Alignment: look at the normal lordosis, and also look at the posterior marginal line for a slip of vertebrae out of place.

Vertebrae: what is the quality of the marrow signal? Increased or decreased signal may be associated with metastatic tumor or discitis/osteomyelitis, or the modic changes of severe disc degeneration at the vertebral end plates.Lumbar MRI T2 Sagittal

Conus: evaluate the position and caliber of the conus. A thickened conus may herald an intramedullary tumor such as ependymoma. The conus usually terminates about L1-2.

Cauda equina: Is there stenosis of the central spinal canal, or clear cut compression of the cauda equina? The CSF signal is normally generous at all levels of the spine. Loss of CSF signal is the hallmark of spinal stenosis. On axial images the canal itself may have a triangular, trefoil, appearance.

“In  this lumbar MRI T2 weighted sagittal, there is a normal lordosis, with a 7 mm anterolisthesis of L4 on L5, with abnormal high signal in the L4 and L5 vertebral bodies. The conus ends at L1-2 and appears normal in caliber and signal. There is moderate stenosis at L4-5. Except for L4-5, the discs are normal in height and signal. The intervertebral foramen are not evaluated on this midline sagittal image.”

Disc: a herniated disc is “protruded” if the bulge is wider than it is deep, or “extruded” if deeper than it is wide. Evaluate all the discs, not just the most obvious one.

Foramen: Look at the lateral slices on the T1 sagittal. Do you see the intervertebral (neural) foramen? It should be patent. You will see a white “fat pad” at each opening, with the dark nerve root coursing through. Loss of the white fat signal suggests impingement of the nerve in the foramen.

Lumbar MRI T1 sagittalLumbar MRI T1 axial” Left lateral sagittal and axial MRI T1 weighted images show obliteration of the fat signal in the L4-5 intervertebral foramen, confirmed on axial imaging through the L4-5 disc where a left lateral extrusion of disc is identified.”

Head CT: a Systematic Reading

How to read a Head CT

BoneAirWaterBrain – and sometimes Contrast

CT Head is the most common cranial imaging study you’ll see. It’s as common in neurosurgery as a chest xray is in internal medicine. And just like the chest xray, you need to approach it systematically. A systematic reading of the images will save you from the common error of looking only at the most obvious abnormality to the neglect of other significant findings. Like seeing an obvious meningioma on the parietal convexity, and missing a smaller meningioma at the optic nerve.

All that to say, you’ve got to approach the head CT in a systematic fashion to avoid costly mistakes.

So here’s an approach: BoneAirWaterBrain – and sometimes Contrast. Today we start with bone windows.

CT head: Bone window


Start with bone windows and look for fracture, especially around the orbits and zygomatic arch. Don’t mistake normal skull suture lines for fractures, but remember that some fractures occur at the suture. Look for widening of the suture or displacement of the fracture.


Keep it on bone windows, but this time look at the air spaces in the head, specifically where air should be: the sinuses and mastoid air cells, looking for air-fluid levels which might suggest a CSF leak. Now look for air where it should not be: at the meninges, especially at vertex, along the interhemispheric fissure, and along the frontal convexity. Air appears jet-black on CT, whether bone or brain windows.


Now with the window set for brain, the CSF spaces should be examined for size and symmetry. If the lateral and third ventricles are abnormally large, consider normal pressure hydrocephalus.

CT head: brain window

If the temporal horns of the lateral ventricles are enlarged, think about acute obstructive hydrocephalus. If you see asymmetry of the lateral ventricles, or the fourth ventricle is not midline, you have evidence of mass effect.


Examine the brain tissue. Sometimes you can differentiate gray and white matter along the cerebral convexity. Look for the hyperdensity of an acute intraparenchymal hemorrhage, or calcifications of an oligodendroglioma. A hypodensity suggests ischemic stroke, but an acute CVA will present with a NORMAL CT. The CT changes do not appear for 24-28 hours after the stroke. In the image below: “There is a hyperdensity deep within the right cerebral hemisphere, with mild edema and mass effect, without midline shift.”


Use contrast for tumor or infection (abscess). But in most cases, if tumor or abscess if suspected, you’ll get an MRI without and with contrast anyway, so skip the CT contrast. Contrast is most useful in a CT-Angiograpy for evaluating possible aneurysm or AVM. For example, if CT for evaluation of a headache reveals a subarachnoid hemorrhage, immediately add contrast for a CT-Angiogram to search for an aneurysm.

CT head: non-contrastCT head: with contrast

The CT on the left is without contrast. The right image reveals peripheral enhancement of this deep right lesion. “There is a peripherally enhancing mass deep within the right cerebral hemisphere, with marked effacement of the right lateral ventricle and 8 mm right to left midline shift.”

In approaching a head CT, read it systematically: BoneAirWaterBrain – and sometimes Contrast.