Consultant Teachings

Consultant Teachings No. 4: "I'm Dizzy"

Clinical Scenario: It’s 3 AM in the ED when a 70 year old male with a history of hypertension comes in complaining of dizziness. You spend 10 minutes trying to get him to describe his dizziness, getting various descriptions of “lightheaded”, “spinning”, “imbalanced”, with him eventually saying “I’m just dizzy doc!!!”. The dizziness was described as sudden onset and had been constant for an hour, but had spontaneously resolved on arrival to the ED. During the episode, he had difficulty standing and stated that it felt like he would fall if he "didn’t hold onto something". He also noted some mild nausea and diaphoresis. Finally, he complained of a headache, though he has a long history of similar headaches. His initial head CT showed no acute process. 

Clinical Question: How do you evaluate a patient with acute dizziness?

Discussion & Literature Review

Dizziness and vertigo make up about 4% of chief complaints in the emergency department (ED) [1]. This chief complaint can be caused by pathology in many different body systems, and that pathology can range from benign to acutely life-threatening. For patients presenting to an ED with dizziness, affected systems include otologic/vestibular (32.9%), cardiovascular (21.1%), respiratory (11.5%), and neurologic (11.2%) as the top four diagnostic groups [2].

Dizziness Conundrum: Despite dizziness being a relatively common complaint, it can be very challenging to work up and manage. Traditional teaching on the evaluation of dizziness is to rely heavily on the quality of the dizziness, whether it is “spinning”, “lightheaded” or other similar descriptors [3]. However, this has been shown to be an ineffective means of establishing a differential diagnosis and may lead to dangerous misdiagnosis. Emergency department physicians (including residents) have been specifically studied and found to demonstrate over-reliance on symptom quality leading to subsequent high-risk reasoning [4,5]. There is also evidence that patients with the two most common vestibular disorders (benign paroxysmal positional vertigo (BPPV) and acute peripheral vestibulopathy) are often managed sub-optimally both in terms of diagnostic testing and prescribed treatment in the ED [6]. These studies suggest an opportunity to improve the emergency management of dizzy patients. 

History is Everything In the Dizzy Patient: As in all of medicine, obtaining an accurate and useful history is the single most important step in establishing the diagnosis of a patient with dizziness. The quality of dizziness lacks specificity in ED patients; one study found that patients describe their dizziness in multiple ways if given multiple options, may change their description of the dizziness if asked again only 5-10 minutes after initial questioning, and answer open-ended questions with vague or circular answers [7]. 

As opposed to the quality of symptoms, patients have been found to more reliably answer questions about the timing and triggers of their dizziness. This had led to the formulation of the “timing and triggers” model of history taking in the evaluation of a dizzy patient [8]. The goal of history-taking in this model is to identify the patient as having one of four syndromic patterns of dizziness:

· acute, spontaneous, prolonged (also known as the acute vestibular syndrome) 
· episodic, positional 
· episodic, spontaneous 
· chronic unsteadiness [8]. 

When asking about timing, attempt to clarify whether the dizziness is sudden or gradual onset, episodic or continuous, the duration of symptoms, and the frequency of symptoms. If the symptoms are episodic, clarify how long each episode lasts (seconds, minutes, hours, days) and make sure to ask if they completely return to normal between episodes or if they have constant symptoms with exacerbations. When asking about triggers, it is important to define true triggers as opposed to exacerbating factors. A common exacerbating factor is any form head movement, which generally worsens all forms of acute vestibular dizziness, so does not often help establish a diagnosis. However, if specific movements (i.e. rolling over in bed or changing posture) trigger the dizziness, this can lead to a diagnosis.  

Examination Tools and Tips: On physical examination, general medical and neurologic screening exams are important. Focal abnormalities on these exams may suggest a diagnosis (i.e. unilateral weakness or ataxia may suggest stroke, new cardiac murmur may suggest myocardial infarction or aortic dissection). However, there are specific physical exam maneuvers that can also be performed. The most commonly employed is the Dix-Hallpike maneuver to evaluate for benign paroxysmal positional vertigo (BPPV). This should be employed only if the patient describes episodic dizziness. The Dix-Hallpike maneuver will worsen the already-present spontaneous nystagmus during the acute vestibular syndrome, but this should not be taken as a positive test. The other test an ED provider should be familiar with is the HINTS-Plus exam [9]. This is a three step test of skew deviation, nystagmus, and head impulse testing (video links to a positive head impulse test, which suggests a peripheral etiology) combined with an assessment for unilateral hearing loss. This test is concerning for a central etiology with the presence of skew deviation, direction changing or vertical nystagmus, a negative head impulse test, and/or new unilateral hearing loss. In the evaluation of the acute vestibular syndrome, this bedside test is more accurate in the acute setting than MRI for diagnosing a posterior circulation stroke. Another physical exam pearl is that some patients can suppress nystagmus with visual fixation, so removing fixation can bring out their nystagmus. An easy way to do this is to turn off the lights and use your ophthalmoscope, which will block fixation and give you a magnified view of the eye for easier visualization of the nystagmus.

Summary and differential diagnosis: Once a patient’s complaints have been characterized by history as one of the four syndromic patterns discussed above, the differential diagnosis is much more limited. The physical examination assesses for specific diagnoses, which then guides further workup and treatment.

Source: Newman-Toker, D. E., Symptoms and signs of neuro-otologic disorders, Continuum (Minneap Minn), 2012, 18(5 Neuro-otology):1016-1040.

Submitted by Alex Dietz, Neurology PGY-4
Faculty Reviewed by Peter Panagos
Everyday EBM Editor: Maia Dorsett, PGY-4

[1] Saber Tehrani, A. S., Coughlan, D., Hsieh, Y. H., Mantokoudis, G., Korley, F. K., Kerber, K. A., Frick, K. D., et al., Rising annual costs of dizziness presentations to U.S. emergency departments, Acad Emerg Med, 2013, 20(7):689-696.
[2] Newman-Toker, D. E., Hsieh, Y. H., Camargo, C. A., Pelletier, A. J., Butchy, G. T. and Edlow, J. A., Spectrum of dizziness visits to US emergency departments: cross-sectional analysis from a nationally representative sample, Mayo Clin Proc, 2008, 83(7):765-775.
[3] Kerber, K. A. and Newman-Toker, D. E., Misdiagnosing Dizzy Patients: Common Pitfalls in Clinical Practice, Neurol Clin, 2015, 33(3):565-575.
[4] Newman-Toker, D. E., Charted records of dizzy patients suggest emergency physicians emphasize symptom quality in diagnostic assessment, Ann Emerg Med, 2007, 50(2):204-205.
[5] Stanton, V. A., Hsieh, Y. H., Camargo, C. A., Edlow, J. A., Lovett, P. B., Lovett, P., Goldstein, J. N., et al., Overreliance on symptom quality in diagnosing dizziness: results of a multicenter survey of emergency physicians, Mayo Clin Proc, 2007, 82(11):1319-1328.

[6] Newman-Toker, D. E., Camargo, C. A., Hsieh, Y. H., Pelletier, A. J. and Edlow, J. A., Disconnect between charted vestibular diagnoses and emergency department management decisions: a cross-sectional analysis from a nationally representative sample, Acad Emerg Med, 2009, 16(10):970-977.
[7]Newman-Toker, D. E., Cannon, L. M., Stofferahn, M. E., Rothman, R. E., Hsieh, Y. H. and Zee, D. S., Imprecision in patient reports of dizziness symptom quality: a cross-sectional study conducted in an acute care setting, Mayo Clin Proc, 2007, 82(11):1329-1340.
[8] Newman-Toker, D. E., Symptoms and signs of neuro-otologic disorders, Continuum (Minneap Minn), 2012, 18(5 Neuro-otology):1016-1040.
[9] Saber Tehrani, A. S., Kattah, J. C., Mantokoudis, G., Pula, J. H., Nair, D., Blitz, A., Ying, S., et al., Small strokes causing severe vertigo: frequency of false-negative MRIs and nonlacunar mechanisms, Neurology, 2014, 83(2):169-173.

Title Image source: wikipedia.

Consultant Teachings No. 3: Evaluation of Tendinous Hand Injuries for the Emergency Provider

Clinical Case:  You are working in a community emergency department one evening when a woman presents with a laceration across the fingerpad of her right thumb that she sustained after falling onto a piece of glass.  The laceration itself is pretty small - about a centimeter across - and has minimal bleeding.   The X-ray ordered by the triage nurse is negative for retained foreign body.  Before you just sew this up and send the patient on her way, you appropriately decide to do a thorough hand exam, including for tendonous injury.  The patient keeps saying that its hard to bend her finger because it hurts...
Consultant Teaching: Tendon Injuries to the hand are often complex entities that are subject to ongoing research regarding optimal procedures for management and rehabilitation. The flexor and extensor tendon anatomy is quite complex. Both are divided into numerous “zones” created to help clarify the optimal treatment, which can vary markedly depending on injury location. Missed tendon injuries increase morbidity by complicating later management and are therefore a leading cause of malpractice claims in the world of Emergency Medicine. The most important and fundamental aspect of evaluation in these patients is a detailed hand exam. Outlined below is a guide for the evaluation and management of any patient presenting to the ED with a suspected hand injury.

Flexor Tendon Injuries
The first step is to obtain a detailed history of the mechanism of injury. Was the injury caused by a rusty farm knife or a sharp chard of glass? What was the position of the patient’s hand when the injury occurred? This is a frequently missed point to mention. You can imagine that, if the patient was lacerated with flexed fingers while gripping a knife, the location of the tendon injury itself may be in a very different location than the skin laceration when evaluating the hand in a more extended posture. Just because you can no longer see the damaged tendon in the wound doesn’t mean it’s not there.

Step 1: Observation 
Evaluate the location and depth of the laceration. Look at the resting posture of the hand and the
patient’s digital cascade. When in doubt, you can usually find clues by looking at the resting finger position of the uninjured hand. Your clinical suspicion should be raised if a particular finger rests in a more extended position relative to the others.

Step 2: Passive Range of motion
These hand injuries can be really painful. A good place to start is assessment of passive motion with a maneuver that elicits the tenodesis effect. Try it on yourself - With a relaxed hand, when you passive flex your wrist, your MCP/PIP/DIP joints will extend. Similarly, wrist extension will cause passive flexion of those digits. If you passively extend the patient’s wrist and there is persistent extension of the DIP or PIP joints, you may have a flexor tendon injury in that digit. 

Step 3: A detailed (ie purposeful) neurovascular exam 
Flexor tendon injuries are frequently associated with neurovascular injury because of the palmar
location of these structures. The best way to assess nerve function is with a two-point discrimination exam. This can easily be performed with a paper clip. Remember that each finger has proper digital nerves on its palmar aspect on both the radial and ulnar sides: test them both. *Tip 1* If you get abnormal results that don’t make sense given the injury, test the other hand! Your patient who forgot to mention his terrible neuropathy will appreciate this. *Tip 2* Under NO circumstances should a digital block be performed if you are planning to consult the hand service on call. If analgesia is an issue, let the hand service know and proceed with necessary oral/IV medications until your consulting service is able to evaluate the patient’s neurovascular status. This is not only important for our documentation, but is critical for possible surgical planning.

Sensory territories of the hand (Source: wikipedia)
There are multiple ways to assess the vascular status. Assessment of cap refill, a digital Allen’s test (same concept as the wrist, but with compression of the radial and ulnar palmar arteries of each finger) and pulse oximetry can all help establish whether or not a concomitant vascular injury is present.

Step 4: Flexor Tendon Exam
A quick anatomy review is necessary here because, in the hand, form truly follows function. The flexor digitorum profundus (FDP) and superficialis (FDS) tendons are both extrinsic hand muscles that power finger flexion. The FDP lies deep to FDS and then attaches distally to the distal phalanx of the 2nd-5th digits. The FDS attaches at the base of the intermediate phalanx of these digits. Why is that important to know for your physical exam? Since these muscles share a common belly and are intimately associated with one another, you must carefully isolate the desired tendon on each digit. Asking a patient to “wiggle their fingers” is an easy way to improperly assess hand function and miss isolated tendon injuries. To test the FDS: all adjacent digits must be held with all joints in extension while the patient flexes the finger at the PIP joint. To test the FDP: hold the middle phalanx in extension while asking the patient to flex just their distal phalanx. Another reason not to digital block these patients is that pain with these movements may clue the examiner into a possible partial tear or laceration.

For completeness, it is also important to document motor testing for all muscles with separate nerve innervations, regardless of its proximity to the wound in question.

Extensor Tendon Injuries 
Like the flexor tendons, these also can be diagnostic challenges due to the complex anatomy of the extensor mechanism. This region is comprised of extrinsic muscles that power digit extension, like the extensor digitorum communis (EDC) and an extensor aponeurosis with multiple connecting bands and ligaments. Again, a detailed history will provide valuable insight and context for your exam. Is it a result of a fight-bite injury? A crushing mechanism?

The general principles of the physical exam addressed above regarding observation, passive range of motion and a detailed neurovascular exam still apply. As diagrammed in the image above, for the dorsal hand, it is especially important to assess both the radial and ulnar nerves.

With regard to hand posture, take note if there is a resting flexed position of the digit, a mallet finger, or boutonniere deformity. This should heighten your suspicion for a tendon injury.

Assessment of the Extensor Tendon 
A few important considerations are noteworthy here. First, do not be fooled by the action of the lumbricals! Remember, these muscles provide extension of the PIP and DIP joints via the lateral bands. Have the patient lay their hand flat on a table (extends the MCP joint and helps remove the influence of lumbricals) and extend at the MCP joint against resistance. Extension along an affected digit may still be possible even after complete laceration, due to the multiple contributions to the extensor mechanism. Look closely for a lack of hyperextension or differential extension in the affected finger that may be a sign an extensor tendon injury has occurred. The junctura tendinae are intertendinous fascial connections located around the MCP joint that attach tendons of the EDC and help coordinate their movements. This anatomic structure is important to keep in mind because the junctura may allow for some extension of an injured digit if the tendon injury is proximal to them.

Lastly, if you are concerned about an injury to the “central slip” (eg. a lac or crush injury to the middle phalanx), then an Elson test can be performed. To do this test, flex the PIP 90 degrees over a table and have them extend against resistance. If the central slip is intact, the DIP joint will be supple. If it is ruptured, there will be weak extension of the PIP and a rigid DIP due to the action of the lateral bands.

So, I did my hand exam… What next? Management of these injuries is often multifactorial and depends on the location of the injury, the structures involved, patient and other factors that are beyond the scope of this post. Doing a correct and detailed physical exam is the first, and most important, step in making sure a patient doesn’t walk out of the ED with an undiagnosed tendon or neurovascular injury.  When practicing in the community, if you suspect that there is an associated tendonous injury based on your clinical exam, clean and repair the laceration as you otherwise would but subsequently place the patent in a dorsal blocking splint, with 15-20 wrist flexion with the hand in intrinsic plus position (MCPs at 70-90 degrees and DIP/PIP straight) and make sure they have follow-up with a hand surgeon.  
At the end of the day, it’s important to keep a high level of suspicion - a referral to a hand surgeon for a suspected tendon injury is just as valid as a referral for a definite tendon injury. 

Check out these videos:
Tenodesis effect: 
Elson test:
Generic hand exam:

Submitted by Chris Cosgrove, MD. Ortho PGY2
Reviewed by: Daniel Osei, MD. Hand Attending

EverydayEBM Editor: Maia Dorsett (@maiadorsett)

Consultant Teachings No. 2: Thoracolumbar Spinal Fractures - A Spine Consult Isn't Always Necessary

Clinical Scenario:  You are working one evening in the emergency department when an intoxicated young female is brought in by EMS after being involved in a reportedly high speed MVC.  She is clinically intoxicated, uncooperative and tachycardic.  She gets a pan-scan CT which identifies some facial fractures and isolated transverse process fractures of the thoracic spine.  As you decide on the next steps to take care of the patient, you debate whether to discuss the patient with a Spine specialist.

Clinical Question: Which spinal fractures should you discuss with a Spine specialist?  Are there some that do not require any intervention at all?

Literature Review:  With the increased availability and increased utilization of CT scanners in the ED, it has become common practice to “pan-scan” patients who present after a trauma, especially those patients who are obtunded/intoxicated or present following a high risk mechanism.  The use of the CT scan to identify thoracic or intrabdominal injuries has concomitantly lead to an increase in diagnosis of fractures of the thoracic and lumbar spine.  As an example, in one retrospective study conducted in the UK of 303 blunt trauma patients who had a Chest/Abdomen/Pelvis CT performed, only six scans (2%) identified thoracic injury and four (1.3%) demonstrated intrabdominal injury while 51 scans (17%) demonstrated an injury to the thoracolumbar spine [1].

With respect to screening for thoracolumbar spinal injuries specifically, the Eastern Association for the Surgery of Trauma practice guideline now recommends CT scan as the primary imaging modality [2]. This is based on a body of evidence that strongly supports that CT scan is more sensitive than X-ray for detection of thoracolumbar spinal injuries.  For example, in one small German study of 107 minor trauma patients, radiographs had a sensitivity of only 49.2% and specificity of 54.7% for thoracolumbar spinal injury compared with CT scan which served as "gold standard" [3].

While CT scan is more sensitive, not all the spinal fractures that are found are clinically significant (i.e. requiring spine precautions or bracing/surgical intervention) [4].  For example, in the small German study cited above X-ray alone missed 16/28 fractures of the the mid thoracic spine, but none of these were considered  unstable [3].  Of the 94 fractures identified in 51 patients by Chest/Abdomen/Pelvis CT in the UK study, 43 (46%) were considered not clinically significant [1].  Thus, the increased sensitivity of our diagnostic evaluation of trauma not only increases our detection of clinically important fractures, but otherwise stable spinal trauma.

Spine consultation for certain types of stable spinal injuries often comes at the expense of increased patient wait times, prolonged spinal precautions,  increased institutional cost, decreased patient satisfaction, and possibly even poorer outcomes if such consultation delays a patient’s transfer to the floor or ICU [4].   Below is a guide to approaching and managing two types of commonly seen fractures in the Emergency Department.

Transverse Process Fractures  

Source: www.

Transverse Processes (TPs) of the vertebrae primarily function as sites of paraspinal muscle and ligament attachments. They are part of the posterior column in the classic Denis “three column” classification, which divides the spinal column into anterior, middle and posterior structural elements. The vertebral body consists of the anterior and middle columns and is the main axial load bearing part of the spinal unit. The posterior column consists of the elements behind the vertebral body, with the most important components being the pedicles, facet joints and ligamentous complex. Stability for the spinal column is maintained through a series of attachments between the various spinal elements (anterior, middle and posterior). An isolated TP fracture is a stable fracture and does not compromise spinal stability. Additionally, isolated TP fractures are not associated with neurologic deficits. The spinal cord and nerve roots are not in proximity to the TPs, nor are they at high risk of displacing in a manner that would put the nerve root or cord at risk.

A small 2008 retrospective study from the University of Missouri looked at a cohort of 84 patients with TP fractures; 47 were isolated and 37 were associated with other spine fractures [5]. In this study, no patients with isolated TP fractures required surgery or bracing for spinal stability. Furthermore, none of these patients had any neurologic deficits. The authors concluded that conservative management of isolated TP fractures was appropriate, without the need for orthopaedic or neurosurgical consultation. However, if the TP fracture is associated with another spinal fracture such as a vertebral body fracture, a specialist consultation is warranted for treatment recommendations regarding the associated injury, but not necessarily the TP fracture itself. Of course, a cervical TP fracture that extends into the transverse foramen also necessitates additonal imaging and likely spinal consultation, as it may warrant a CT angiogram for evaluation of vertebral artery damage.

Compression Fractures

Vertebral compression fractures are the most common fragility fracture, affecting approximately 25% of people over the age of 70. Compression fractures are a result of axial force on the anterior column that results in a wedge deformity of the vertebral body. The vast majority of compression fractures do not require surgical intervention. Moreover, these fractures are often stable due to their impacted nature. No study has proven that bracing vertebral compression fractures prevents further vertebral collapse, decreases pain, or improves patient satisfaction. Treatment of most vertebral body compression fractures can focus on reducing associated pain with appropriate pain medications. A thorough approach to a patient presenting with an acute compression fracture should include the following:

1: Patient factors: What was the mechanism of injury (simple fall or high-energy injury)? Is the patient ambulatory, bed or wheelchair bound? Are there significant medical comorbidities (ie morbid obesity, extensive pulmonary disease) that would make bracing an ineffective or even dangerous treatment option? Is the patient’s pain controlled enough to obtain an accurate neurologic exam? Is the patient tender over the spinal segment in question?

2: Fracture factors: Is the fracture stable or unstable? The best way to evaluate is to use the patient’s own physiologic forces to see if there is further displacement of the fracture. Barring any neurologic deficits, plain supine AND upright radiographs of the affected area should be obtained. The goal is to see if there is any significant height loss or increased kyphosis between the series. If not, it’s a safe bet that the fracture is stable.

Given a stable fracture, the next step is determined primarily by patient comfort level. If the patient is able to tolerate sustained physiologic loads (ie sitting or standing), it is reasonable to send them home with observation only, no bracing required. Follow up could be provided by their primary care provider or PM&R. If they are in too much pain to stand or sit despite appropriate analgesia, an extension orthosis (like an off-shelf TLSO) is sometimes beneficial and can be provided by the spine consultant on call. If the compression deformity is acute and deemed to be unstable, if there are any neurologic deficits or other associated spinal pathologies, certainly a spine consultation is necessary and appropriate at that time.

Take Home Points:  The increased use of CT imaging, especially in trauma, may lead to the identification of injuries that do not necessarily warrant intervention other than pain control.  For neurologically intact patients, it is useful for the emergency physician to be aware of which fractures warrant either bracing or surgical intervention as unnecessary  consultation can lead to prolonged length of stay and increased cost without significant benefit to the patient.

Submitted by Chris Cosgrove, Orthopedic Surgery PGY-2
Faculty Reviewed by : Lukas Zebala, MD, Assistant Professor, Orthopaedic Surgery

Everyday EBM Editor Maia Dorsett (@maiadorsett)

1. Venkatesan, M., Fong, A., & Sell, P. J. (2012). CT scanning reduces the risk of missing a fracture of the thoracolumbar spine. Journal of Bone & Joint Surgery, British Volume, 94(8), 1097-1100.
2. Sixta, S., Moore, F. O., Ditillo, M. F., Fox, A. D., Garcia, A. J., Holena, D., ... & Cotton, B. (2012). Screening for thoracolumbar spinal injuries in blunt trauma: An Eastern Association for the Surgery of Trauma practice management guideline. Journal of Trauma and Acute Care Surgery, 73(5), S326-S332.
3. Karul, M., Bannas, P., Schoennagel, B. P., Hoffmann, A., Wedegaertner, U., Adam, G., & Yamamura, J. (2013). Fractures of the thoracic spine in patients with minor trauma: Comparison of diagnostic accuracy and dose of biplane radiography and MDCT. European journal of radiology, 82(8), 1273-1277.
4. Homnick, A., Lavery, R., Nicastro, O., Livingston, D. H., & Hauser, C. J. (2007). Isolated thoracolumbar transverse process fractures: call physical therapy, not spine. Journal of Trauma and Acute Care Surgery, 63(6), 1292-1295.
5. Bradley, L et al. Isolated transverse process fractures: spine service management not needed. J Trauma 2008 Oct; 65(4):832-6.

Consultant Teachings No. 1: Acute Neuromuscular Respiratory Failure

Clinical Scenario: You are working in EM 2. It’s 3 AM and a 32 year old woman is roomed with the chief complaint of shortness of breath. She has been getting progressively more short of breath for the past 2 days. She’s also noticed that she just can’t keep her eyes open, though her right eyelid droops more than her left. You notice her head is falling forward. When you question her about that, she says she has had trouble holding it up for 4 days. Your general exam is normal, with no wheezing and normal heart sounds. Her neuro exam shows weakness on eye closure, neck flexion, and neck extension. She has no weakness anywhere else.

Clinical Question: How should acute neuromuscular respiratory failure be evaluated and managed?

Literature Review
Neuromuscular respiratory failure is relatively rare but constitutes a medical emergency with significant morbidity and mortality, particularly with delays in recognition. The most common causes are acute inflammatory demyelinating polyneuropathy (e.g. Guillain-Barre syndrome, GBS) myasthenia gravis (MG), motor neuron disease (e.g. amyotrophic lateral sclerosis, ALS) and some forms of myopathy. A study in Northern Ireland found the causes of acute respiratory failure due to neuromuscular conditions were GBS (62%), MG (18%), ALS (9%), then a variety of other conditions (2, 3). Early recognition of these conditions by history and physical exam, combined with specific bedside testing, can help appropriately triage and manage these patients. GBS has an incidence of 1-4 per 100,000 and represents the most common cause of acute paralysis. It is also often missed early in the disease, with patient’s requiring an average of 2 ED visits before diagnosis [1]. GBS can progress from symptom onset to respiratory failure in 48 hours, so early identification is important. The mechanism of respiratory failure is loss of activity of the diaphragm and accessory muscles of respiration, and can often be complicated by aspiration due to craniobulbar weakness. The diaphragm is innervated by the phrenic nerve, derived from the C3-5 nerve roots (remember: “C3, 4, and 5 keep you alive”).

The initial evaluation should begin with a careful history, including the time from symptom onset to ED presentation. When taking the history, it is important to ask specifically about:

1) Drooping eyes (ptosis)

2) Double vision (diplopia)

3) Change in speech (breathy or nasal)

4) Difficulty swallowing including nasal regurgitation (food/liquid coming out the nose)

5) Fatigue with chewing

6) Head drop (inability to support their head)

All of these can be findings of bulbar and high cervical spine pathology, and can be warning signs for impending respiratory failure. The history should also include characterization of weakness in other places (i.e. leg or arm weakness), sensory symptoms (ascending numbness or paresthesias) and autonomic symptoms (new-onset orthostatic symptoms, bowel or bladder retention/incontinence, changes in sexual functioning).

On physical exam, after doing a routine medical exam, specifically test:

1) Eye movements (looking for impairment of extraocular musculature)

2) Eye closure strength

3) Mouth closure strength

4) Tongue strength and palate elevation

5) Assess for a weak cough

6) Neck flexion and extension strength

7) Breath count (ask the patient to count up at a rate of one number per second after taking a full breath. This is a crude estimate of vital capacity, with each number being ~100 ml.)

Numbers 1-5 detect craniobulbar weakness. Neck flexion and extension are well correlated with diaphragmatic strength. Neck flexion weakness correlates with impaired respiratory function, while neck extension weakness should be considered a warning sign of impending respiratory failure.

Laboratory testing: History and exam should guide testing, but a full set of screening labs is generally appropriate (CBC, BMP, HFP). Other bloodwork that can be obtained include CK, TSH, and ESR [4].

Respiratory therapy should measure forced vital capacity (FVC) and negative inspiratory force (NIF). FVC < 20 ml/kg (~ 1- 1.5L) or NIF < -30 cm H20 are warning signs for impending respiratory failure [5].  It is important to discuss the effort provided and the quality of the lip seal with the respiratory therapist that performs the testing.

If there is evidence of severe diaphragmatic weakness (very weak neck extension or low NIF/FVC), it is reasonable to check an ABG or VBG for hypercapnea and a respiratory acidosis, consistent with inadequate ventilation.

If there are signs of impending respiratory failure, it is important to determine if non-invasive ventilation (e.g. BiPAP) or intubation and mechanical ventilation is most appropriate. This is a decision that should be made with the consulting neurologist and with the admitting ICU. However, if the objective findings (NIF/FVC and ABG) or trajectory (rapid deterioration) are poor, it is reasonable to electively intubate in the ED instead of an emergent intubation in the ICU.  Concurrent craniobulbar weakness and/or a weak cough are relative contraindications for use of non-invasive ventilation given the increased risk of aspiration.

Intubation in patients with neuromuscular weakness carries special risks.   In myasthenia gravis, due to a complex interaction between the number of ACh receptors at the neuromuscular junction, antibodies inhibiting those receptors, and the effects of treatment such as plasmapheresis and enzyme inhibitors, neuromuscular blockade can have unpredictable effects.
Image source:
Myasthenia patients have net loss of AChR at the neuromuscular junction (see Figure), making these patients relatively resistant to succinylcholine.  However, in cases where myasthenic crisis is treated with plasmapharesis, which also incidentally rcmoves the enzymes required for breakdown of paralytic agents, patients can have very  prolonged neuromuscular blockade.  While the effect of succinylcholine can go either way, patients with myasthenia gravis can be extremely sensitive to nondepolarizing blockade (one study found that the effective dose of vecuronium in MG was 1/5 that in controls) [6,7].

 In addition to the unpredictable effects of neuromuscular agents, patients with neuromuscular weakness is general are at higher risk of developing critical illness myopathy following exposure to paralytics. Avoidance of any paralytic is the goal when intubating a patient with MG, so consider using topical lidocaine with a sedative such as propofol [8]. Patients with GBS often develop significant autonomic dysfunction, with concomitant extreme swings in blood pressure and heart rate [9]. Autonomic dysfunction can be exacerbated during intubation. It is important to avoid treating these swings in blood pressure and/or heart rate unless there is evidence of end organ damage. Treating these rapid swings places the patient at a high risk of iatrogenic injury when their blood pressure or heart rate spontaneously rebounds and this rebound is exaggerated by the medications provided.

Clinical Take home:1) Have a high index of suspicion for neurologic causes of respiratory failure.
2) Check craniobulbar and neck flexion/extension strength in patients in whom you suspect neuromuscular pathology.
3) Check NIF/FVC and an ABG on any patient with a suspected neuromuscular condition and dyspnea.
4) Intubate with a reduced dose of non-depolarizing agent or preferably no paralytics at all
5) Expect heart rate and blood pressure swings, especially during intubation. Don’t treat them unless there is end-organ damage, as they are likely to spontaneously resolve.

Submitted by Alex Dietz, Neurology PGY-3
Additional Review by Jennifer Griffith
Faculty Reviewed by Robert C. Bucelli (Neurology)

Everyday EBM Editor: Maia Dorsett

[1]Noto A, Marcolini E. Select topics in neurocritical care. Emerg Med Clin North Am 2014;32:927-938.
[2]Carr AS, Hoeritzauer AI, Kee R, et al. Acute neuromuscular respiratory failure: a population-based study of aetiology and outcome in Northern Ireland. Postgrad Med J 2014;90:201-204.
[3]Pfeffer G, Povitz M, Gibson GJ, Chinnery PF. Diagnosis of muscle diseases presenting with early respiratory failure. J Neurol 2014.
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[5]Lawn ND, Fletcher DD, Henderson RD, Wolter TD, Wijdicks EF. Anticipating mechanical ventilation in Guillain-Barré syndrome. Arch Neurol 2001;58:893-898.
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