UMEM Educational Pearls - Neurology

• 5 to 10% of TIA victims go on to have a complete stroke within 7 days.

• The following validated ABCD clinical prediction rule can be used to risk stratify your next TIA patient in determining who requires an expedited in-patient work-up:

          Risk Factor                                                                        Score

• Age > or = 60                                                                      1

• Blood Pressure (SBP > 140 and/or DBP > or = 90)                    1

• Clinical Features (choose one)

          -- Unilateral weakness                                                           2

          -- Speech impairment w/o weakness                                       1

          -- Other                                                                               0       

• Duration of Symptoms (minutes)

          -- > 60                                                                                2

          -- 10 to 59                                                                           1

          -- < 10                                                                                0

                                                                                              Total 0-6

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• Patients who have recently undergone aneurysmal coiling commonly present to the ED with complaints of new or worsened focal neurologic deficits that may be suggestive of stroke.

• Aneurysms can be stabilized by clipping or coiling them.  Coiling is performed in a minimally invasive manner, wherein platinum (a material that can be visualized radiographically and is flexible) coils are deployed into the bulb of the aneurysm, via femoral artery cannulation.

• The relative risk of mortality or morbidity at one year post-coiling was found to be 22.6% less than that associated with clipping.  The latter is an older, more invasive technique requiring craniotomy and direct manipulation of the brain.

• Hemorrhage is a less likely complication related to aneurysm coiling, thus your indication for a non-contrast Head CT in these patients would most appropriately be "rule out infarct" rather than "rule out bleed." 

• Brain infarct is the more common complication of this treatment, and results from the accidental embolization of plaque during the coiling procedure.

• Here are a couple of great links with illustrated overviews of the process of coiling, including a real time You Tube clip:
  
  http://www.brainaneurysm.com/aneurysm-treatment.html
  
  http://www.youtube.com/watch?v=Mvy8g_oDbbk

• Syncope is defined as a transient loss of consciousness and accounts for an estimated 1% to 3% of emergency department (ED) visits.
   
• While syncope typically is of benign origin, it occasionally signals significant mortality and morbidity, which can make determining the disposition of syncope patients a challenge.
   
• The San Francisco Syncope Rule (96% sensitivity, 62% specificity) is a clinical tool used to determine which syncope patients are at low risk for a short-term (7-day) serious outcome (i.e. MI, arrhythmia, PE,  stroke, SAH, significant hemorrhage, any condition causing or likely to cause a return ED visit or hospitalization).
  Specifically, absence of all of the following 5 findings (acronym CHESS) were associated with no serious outcome within 7 days of the syncopal episode according to this rule:
  • Congestive heart failure
  • Hematocrit less than 30
  • EKG Abnormalities
  • Systolic BP less than 90
  • Shortness of breath
     
• While this decision rule, in addition to one's clinical skill, may be used as a guide in caring for and dispositioning syncopal patients, know that its ability to be extrapolated to a general population of ED patients has yet to be validated.

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• The majority of those afflicted with bell palsy experience neurapraxia or a local nerve conduction block, which usually predicts a prompt and full recovery.  80% to 90% of Bell Palsy patients experience recovery without any noticeable disfigurement within 6 weeks to 3 months.

• Some Bell Palsy patients experience axonotmesis, disruption of the axons, which increases their risk of an incomplete recovery.

• One is at higher risk of developing sequelae in the following scenarios: 

          --  Age greater than 60 years

          --  Diabetes

          --  Decreased taste or salivary flow on the affected side

          --  Complete paralysis

• Common post-Bell Palsy sequelae that you may see clinically include:

          --  Synkinesis - abnormal contracture of facial muscles with smiling or

               closing eyes; may cause slight chin movement with blinking, eye closure

               with smiling, contracture around mouth with blinking.

          --  Crocodile tears - lacrimation while eating.

          --  Hemifacial muscle spasms - tonic contractures of affected side of face, 

               rare, often seen during times of fatigue, stress, or while sleeping.

• Bell Palsy is the most common cause of unilateral facial weakness.

• It is caused by edema and ischemia causing compression of the facial nerve (cranial nerve seven).

• While Bell Palsy is by definition an idiopathic facial palsy, the etiology is often infact discovered and attributed to conditions such as Lyme Disease, Herpes Simplex Virus, and HIV.

• Classic symptoms of Bell Palsy include:

          -- acute onset of unilateral upper and lower facial paralysis (over 48 hr. period)

          -- posterior auricular pain

          -- decreased tearing

          -- hyperacusis (due to stapedius muscle weakness)

          -- taste disturbances

• Bell Palsy is a diagnosis of exclusion.  If the facial paralysis is isolated to the lower face, if there is associated contralateral weakness, and/or if there is diplopia, a central cause for the symptoms, rather than Bell Palsy, must be strongly considered.

• Neurologic complications affect 30 to 60% of allograft organ transplant recipients.
   
• Many of these complications are related to immunosuppresant medication neurotoxicity.
   
• Calcineurin inhibitors such as tacrolimus (FK-506 or Fujimycin) and cyclosporin are classically associated with the following neurologic disorders:
  • Cranial Nerve Palsy:  Tacrolimus toxicity can cause reversible  internuclear ophthalmoplegia.
  • Movement Disorders:  Tacrolimus and cyclosporin often cause tremor, which can be further compounded by the development of asterixis should the patient also have significant renal or hepatic insufficiency.
  • Visual Abnormalities:  Cortical blindness, visual disturbances, hallucinations, retinal toxicity, and optic neuropathies have all been attributed to calcineurin inhibitor toxicity.  Opsoclonus (rapid, involuntary, uncontrolled, multivectorial eye movements) has specifically been associated with cyclosporin neurotoxicity. 
     

• Neurotoxicity related to immunosuppresant drug therapy is most likely to occur early after transplantation and during a rejection episodes, times at which medication doses are typically at their highest.  Dose adjustment often results in resolution of symptoms.
   
• Be sure to check drug levels of immunosuppresant medications, particularly when a transplant patient presents with a neurologic disorders.

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• Akathisia is an adverse effect sometimes associated with the administration of medications such as neuroleptic anti-psychotics (i.e. chlorpromazine (Thorazine); haloperidol (Haldol); ziprazidone (Geodon)) and dopamine-blocking anti-emetics (i.e. metoclopramide (Reglan); prochlorperazine (Compazine)).

• This unpleasant symptom complex consists of restlessness and agitation, the severity of which correlates with the dose of the causative agent.

• Treatment classically consists of stopping or decreasing the dose of the causative agent and administering diphenhydramine (Benadryl).

• Benzodiazepines, beta blockers, and the antihistamine cyproheptadine have also been used with success.

• The following instrument, a modified version of the Prince Henry Hospital Scale of Akathisia, can be used to clinically assess for akathisia in a standardized fashion:

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• It is incumbent that emergency physicians be aware of and utilize as appropriate all available tools in the critical, yet challenging evaluation and management of acute ischemic stroke (AIS) patients.
   
• While non-contrast head CT remains the primary modality used in the initial evaluation of these patients, CT angiography (CTA) and MRI with diffusion are rapidly becoming more acutely available because they provide more exact and accurate information, which directly affects the crucial decisions that have to be made in order to provide effective and expedient care.
   
• CTA provides imaging of the entire intra and extra cranial circulation beginning at the aortic arch to the Circle of Willis, and can be performed in less than 20 seconds.  Within minutes, these imags can be re-constructed to reveal vascular stenosis and occlusions.
   
• MRI is typically not as rapidly accessible as CT, but there are scenarios wherein the additional time spent to acquire this modaility yields significant clinical merit.  While a full brain MRI may take up to an hour, acquisition of the MR diffusion portion of the scan (which highlights focal areas of acute infarct) requires less than 10 minutes.    

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• Patients with severe or rapidly progressive weakness due to a Myasthenia Graves (MG) exacerbation should be admitted to an intensive care unit.
   
• Acute MG patients' forced vital capacity (FVC) should be monitored every 2 to 4 hours to accurately assess the function of their respiratory muscles.
   
• FVC can easily be measured at the bedside, particularly by a respiratory technician.
   
• Once the patients' FVC is consistently approaching or reaches 15 mL/kg, the patient should be electively intubated in order to ensure protection of their airway.  In an average sized adult, an FVC of 1000 mL is the point at which respiratory failure is eminent.
   
• Arterial blood gas abnormalities are not reliable indicators of respiratory muscle decompensation, and typically occur as a late sign of respiratory failure.
   
• Once the patient is intubated, anticholinesterase medications are typically withdrawn.

• Myasthenia Graves (MG) is an autoimmune disorder wherein antibodies, perhaps created by the thymus, block the acetylcholine receptors at the post-synaptic neuromuscular junction.
   
• The term "myasthenia graves" literally means "severe muscle-weakness" from its Greek and Latin origins.
   
• The clinical hallmark of this disorder is muscle weakness and fatiguability, primarily affecting the facial muscles.
   
• In spite of having personally seen about 3 cases of MG in the ED over the past couple months, this disorder is actually one of the less common autoimmune disorders, affecting 200 to 400 per 1 million persons.
   
• Treatment includes cholinesterase inhibitors, immunosuppressants, and at times, thymectomy.

• One may wonder how to determine whether a patient has limb ataxia in the setting of limb weakness when scoring the NIH Stroke Scale (NIHSS).

• The component of the NIHSS that tests for limb ataxia asks that the patient perform finger to nose and shin to heel testing.

• A patient who does not exhibit any ataxia would receive a score of 0 (zero), which is the best score.

• If the patient does not exhibit any ataxia because he/she has neuromuscular weakness and therefore can't perform the tasks at all, they would also receive a score of 0 (zero) on this component of the NIHSS.

• With regard to following commands, the NIH Stroke Scale (NIHSS) assesses this level of consciousness in part 1C by asking the patient to do the following two things:

          1.  "Close your eyes and now open them."

          2.  "Make a fist and now open it."

• You may repeat the command no more than twice in order to avoid the bias of coaching the patient.

• It's fine to provide some prompting by performing the task yourself while asking the patient to do the same.
   
• This component of the NIHSS is scored as follows:

          0 = performs both tasks correctly.
          1 = performs one task corectly.
          2 = performs neither task correctly.

• The first part of the NIH Stroke Scale assesses level of consciousness in 3 parts, 1A, 1B, and 1C.

• Part 1B assesses orientation by having the patient tell the examiner (1) their age and (2) the month.

• Part 1B is scored in the following manner:

          -- Answers both questions correctly = 0

          -- Answers one of the two questions correctly = 1

          -- Answers neither question correctly = 2

• If patient is unable to speak due to being intubated, having orotracheal trauma, dysarthria, a language barrier, or any other reason other than truly being aphasic, a score of 1 should be assigned.

• A patient's blood pressure should be maintained at less than 185/110 prior to receiving thrombolytics for stroke.

• The following medications should be used to address blood pressure control in these patients:

               Labetalol 10 to 20 mg IV over 1 to 2 minutes, may repeat x 1  

               OR

               Nitropaste 1 to 2 inches

               OR

               Nicardipine infusion at 5 mg per hour, titrate by 0.25 mg/hr at 5 to 10 minute intervals up to a maximum

               dose of of 15 mg/hr.  Once desired blood pressure is achieved, titrate down in increments of 3 mg/hr. 

When performing the NIH Stroke Scale, keep the following conventions in mind:

-- Administer scale items in their exact order.
-- Avoid coaching the patient.
-- Accept the patient's first effort.
-- Be consistent.
-- Score only what the patient actually does.
-- Include all deficits in scoring.

• Fever is present in 80% of cases.
   

• Treatment includes high dose intravenous antibiotics.  Anti-coagulation therapy is controversial and often held.
   

• Mortality is 30% with an additional 30% enduring sequelae such as oculomotor weakness, blindness, and pituitary insufficiency.

• Cavernous sinus thrombosis, one of the three dural sinus thrombosis syndromes, is extremely rare and results from infection often originating from the face, sinuses, dental cavity, ears, and mastoids.

• Cranial nerves III, IV, V1, V2, and VI course along the walls of the cavernous sinus such that extraocular motion abnormalities (palsy/paralysis) commonly manifest with cavernous sinus thrombosis.

• Headache (usually sharp, unilateral, and in the distribution of V1 and V2 branches) is typically the initial presenting symptom, followed by eom palsy, mydriasis, diplopia, periorbital edema, visual abnormalities, mental status deficit, and coma.

• Angioedema occurs in less than 1% of stroke cases treated with tPA.
• Particularly associated with ACE inhibitor and beta blocker (less so) use.
• Symptoms are usually mild affecting the lips, tongue, and oropharynx.
• Check the patient for such symptoms at 45, 60, and 75 minutes post tPA administration.
• When present, consider treating with some or all of the following agents: 
   

             -- Diphenhydramine (Benadryl) 50 mg IV
             -- Ranitidine (Zantac) 50 mg IV
             -- Methyprednisolone (Solumedrol) 50 - 100 mg IV
             -- Racemic Epinephrine
             -- Anesthesia consult re: airway management

• Always be sure to examine a patient's carotid arteries for bruits when concerned about stroke and/or TIA.  Bruits suggest the presence of stenosis.
• Dijk and colleagues found that patients with > 50% carotid artery stenosis are at high rsk for stroke and TIA.
• Bruits are best ascultated by using the bell of the stethoscope and asking the patient to briefly hold their breath while trying to hear the abnormality.
• The American Heart Association recommends that symptomatic stenosis of > 50% undergo carotid endarectomy (CEA) within 2 weeks.  If CEA is contraindicated, stenting should be pursued.  CEA for stenosis of 70% to 99% is typically recommended regardless of symptomatology.

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• Motor function is one of the three neurologic responses assessed by the Glasgow Coma Scale (GCS).
• This response is scored on a scale of 1 to 6, 6 being the best score:          
  • 6 = Obeys commands (does simple things as asked). 
  • 5 = Localizes to pain (purposeful movements towards  painful timuli; e.g., hand crosses mid-line and gets above clavicle when supra-orbital pressure applied).
  • 4 = Flexion/Withdrawal to pain (flexion of elbow, supination of forearm, flexion of wrist when supra-orbital pressure applied. (i.e. pulls part of body away when nailbed pinched)).
  • 3 = Abnormal flexion to pain (adduction of arm, internal rotation of shoulder, pronation of forearm, flexion of wrist, decorticate response).
  • 2 = Extension to pain (adduction of arm, internal rotation of shoulder,pronation of forearm, extension of wrist, decerebrate response).
  • 1 = No motor response.