On Call Pitfalls

On-Call Pitfalls

Things that Kill. Things that Bother.

Calls to the neurosurgery group can be divided into two groups: things that kill and things that bother. Listening for conditions that may become life threatening is a skill that comes with experience. What is “experience?” Paying attention to the things that have happened, often informed by mistakes you have made in the past!

Things that kill

MI. Specifically myocardial infarction in the post operative patient. Surgery is a stress to the body, and the patient with atherosclerotic coronary disease, for example, can be pushed over the edge simply from the physical impact of the surgical event. A cardiac event is suggested by any combination of chest pain, with radiation to the jaw or arm, with diaphoresis, with shortness of breath. Be quick to order a 12-lead EKG, cardiac enzymes, and pulse ox. If you wonder if the patient may be unstable, call the Rapid Response team for an immediate evaluation.

PE. Pulmonary embolism is characterized by chest pain around the ribs, diaphragm, or back, with shortness of breath, tachypnea, and anxiety about breathing, worse with lying, better sitting and leaning forward. Evaluate with pulse ox, ABG, chest x-ray, CT-Angiogram of the chest, and labs. Definitely call a Rapid Response whenever there is respiratory distress.

DVT. Here are the classic hallmarks of DVT: a painful, red, swollen, hot extremity. This is a little tricky to sort out on the neurosurgery service, since many of our patients have pain in an extremity to start with! So when you are called for pain in a leg or an arm, always ask: Is it swollen, red, and hot compared to the other? Order an ultrasound of that extremity to look for DVT, and unless you are sure it is not a DVT, remove the sequential compression device from the leg and keep the patient on bed rest. If a DVT is present, you’ll need to consider anticoagulation and the placement of an IVC filter.

CVA. Acute ischemic stroke presents with new-onset brain symptoms. Weakness or numbness on one side of the body, facial droop, slurred speech, confusion, and vertigo are all signs of a stroke. These symptoms are usually painless, and the patient almost always discounts their significance. Family members will often be the first to mention the changes. Any new onset stroke symptoms require an immediate CT of the head. Even in acute stroke, though, this is expected to be *normal* unless the stroke is hemorrhagic! Sometimes a follow up MRI is ordered with diffusion weighted images to prove the ischemic event. Other diagnostic steps include pulse ox, 12-lead EKG, labs including chemistry, CBC, lipid profile, and HbA1c. Risks and benefits of aspirin therapy can be weighed carefully in the post op neurosurgical patient.

Spinal cord compression and cauda equina syndrome. An epidural hematoma after a spinal procedure is a neurosurgical emergency. In the cervical spine this can follow anterior or posterior surgery. The hematoma compresses the cord causing severe local pain along with weakness, numbness, and spasticity in the extremities, with increased reflexes and sustained clonus. In the lumbar spine an epidural hematoma may compress the cauda equina causing severe local pain and numbness in the saddle region or in the legs, with weakness and depressed reflexes. Either case is a neurosurgical emergency and must be evaluated with immediate plain x-ray to visualize the bone structure and urgent MRI to image post op fluid collections, CSF, and the neural structures.

Drug allergy. A true drug allergy can be a life threatening emergency with anaphylaxis or hemodynamic shock. The lip swelling of angioedema or a macula-papular rash on the chest and trunk can herald an allergic reaction. Treatment begins with stopping the offending agent, a real trick since you usually don’t know which drug is the culprit! So you go with percentages: phenytoin and antibiotics are well known for causing allergic reactions. The next step of treatment is steroids and antihistamines to suppress the body’s allergic response. Above all, you must be mindful to protect the patient’s airway at all times.

Things that Bother

The vast majority of your calls will be for issues of comfort. I’m not minimizing these, but they occupy a different level of urgency. They are important in the patient’s recovery in that they can be obstacles to the patient’s physical progress. Here are the most common.

Pain. An inordinate amount of pain can signal an urgent problem like an epidural hematoma in the immediate post op patient, or infection days to weeks after surgery. After you have ruled out worrisome causes of pain, treat it using the standard drugs in your armamentarium: narcotics, muscle relaxants, anticonvulsants (like gabapentin), antidepressants (like amitriptyline), and sometimes a short course of steroids. Physical options include an ice pack to the surgical site. The PT/OT can instruct the patient in proper body mechanics to reduce pain with movement. The main idea is to control the pain well enough to allow physical progress in recovery.

Nausea. Pain can be nauseating, and the drugs used to treat pain can be nauseating! Nausea may reflect a post operative ileus that can occur after exposure for anterior lumbar surgery. Diagnostic evaluation with KUB can demonstrate an ileus. For the nauseated patient, limit the diet to ice chips or clear liquids until the gut is in better spirits.  Antiemetics and prokinetics are the medications most useful to keep on board, and in severe nausea these can be ordered around the clock for a period as a preventative. A physical technique to help prevent vomiting is slow, steady breathing. If vomiting is imminent, prevent aspiration by having the patient in a side-lying position or elevate the head of bed.

Constipation. There, I’ve said it! This is the number one complication of any hospitalized patient, and you will soon become an expert in preventing and treating constipation. Keep in mind that managing constipation in the *hospitalized* patient is different from the primary care setting. You’ll use docusate (Colace) in all hospitalized patients. Be quick to add polyethylene glycol (Miralax) and senna (Senokot) nightly for mild constipation. Bisacodyl functions like a stick of dynamite in the gut, and you’ll prefer the suppository route to “put the medicine right where it needs to work.” An enema is another option.

Itching. Itching can be an annoying but benign side effect of some medications like narcotics, or it may be a much more significant signal of an allergic reaction. For mild itching, a systemic antipruritic like diphenhydramine or hydroxyzine is useful. I avoid topical antihistamines and steroids because I don’t want my patient slathering medicine around a surgical incision. Blisters will appear with Stevens-Johnson syndrome, which is a life threatening emergency.

Call for help

As a neurosurgery beginner, you won’t have the experience, so learn from the experience of others. Keep your handbooks handy, both neurosurgery and medicine. Be quick to call your attending physician or a seasoned peer for advice. There are dangers and pitfalls lurking everywhere. As the saying goes: Learn from the mistakes of others—you won’t live long enough to make them all yourself.

When to get a CT Head

When to get a head CT?

How do you know when to order a head CT? A patient presents with headache or confusion: should you get a scan now? Here is a mnemonic that can help you know when to get a head CT on a patient with neurological symptoms.

SCAN – NOW. Get a CT Head if . . .

Seizure: new onset seizure

Confusion, or any change in mental status

Acute onset: a “new and different” headache

Nuchal rigidity: the stiff neck of meningitis or subarachnoid hemorrhage

Neuro deficit: any focal neuro change, like unequal pupils or pronator drift

Optic papilledema: a sign of increased intracranial pressure

Worrisome history: like malignancy, anticoagulants, or prior bleed or known lesion

For the patient with complaint of headache, always ask, “Is this the same old headache that’s bothered you so long … or IS THIS NEW AND DIFFERENT?” The “new and different headache” needs a CT.

For the headache patient, always perform a funduscopic exam, looking for optic papilledema, a sign of increased intracranial pressure. Every headache workup needs a funduscopic exam!

Nuchal rigidity is a classic sign of meningitis and is caused by the irritation of the meninges caused by bacteria and white blood cells in the CSF. This irritation is heightened by flexion of the neck, as the meninges are stretched. In a subarachnoid hemorrhage, red blood cells in the CSF cause a similar irritation of the meninges, aggravated by neck flexion. This nuchal rigidity is also associated with Kernig’s sign and Brudzinski’s sign. Any patient with headache and nuchal rigidy requires an immediate CT of the head. (And in the presence of acute illness or fever suggesting meningitis, immediate administration of antibiotics, even before the diagnostic workup is completed.)

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

Discitis

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

Aside

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.

Clear Canvas: A Reader Program for CD images

Clear Canvas: A Reader Program for CD images

Every patient brings their films on CD. It can take forever to let each disc load its reader software and images. A much faster way to get the images is to have a reader program resident on your computer, as a free standing program, pre-loaded, just like Microsoft Word is a free standing program. Then when you insert the patient’s CD, the images will dump into the program. Not only is it the fastest way to get to the images, it also offers the ease of navigating the same software every time, rather than having to figure out the commands of each different reader program.

I am using Clear Canvas, available as a free program from http://www.clearcanvas.ca. When go to their site, you will register for free, then go to downloads. The product you want is the Workstation.

After you download the program, you double click from your desktop to start the program. Insert the patient CD, and cancel the Autoplay feature to keep the disc program from loading. Now, go to Clear Canvas and click the “Computer” tab, and then right-click on the drive containing the disc. Choose “Import.” A progress bar will display. After all the images have come into Clear Canvas, click the “Dicom” tab. Find the patient name and double-click the study you want to view.

I am constantly using the “cross reference lines” feature to see where I am, and of course the “windowing” feature to adjust brightness and contrast. This program has streamlined my office practice!

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

Bone

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.

Air

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.

Water

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.

Brain

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.”

Contrast

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.