UMEM Educational Pearls - Neurology

• 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. 

Below is an edited version of this week's neurological clinical pearl. Somehow the scores and their definitions showed up incorrectly matched.  See corrections below.

• Verbal 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 5, 5 being the best response.
  • 5 = Oriented (responds coherently and appropriately to questions such as name, age, situation).
  • 4 = Confused (responds to questions coherently but with some disorientation and confusion).
  • 3 = Inappropriate words (random articulated speech but no conversational exchange).
  • 2 = Incomprehensible sounds (moaning but no words).
  • 1 = No verbal response.

• Eye function is one of the three neurologic responses assessed by the Glasgow Coma Sacle ( GCS).
• This response is scored on a scale of 1 to 4, 4 being the best response.
  • 4 =  Spontaneous eye opening.
  • 3 = Eye opening in response to speech (not to be confused with eye opening in an asleep patient when prompted with speech; these would receive a 4, not a 3).
  • 2 = Eye opening with painful stimuli (i.e. nailbed pressure, supraorbital compression, and/or sternal rub).
  • 1 = No eye opening.

• Glasgow Coma Scale (GCS) is a validated score intended to provide a reliable and objective method for recording and communicating a patient's consciousness.
  

• It was originally created to assess head injury patients' neurologic status/deficit.
  

• The scale ranges from 3 (deeply unconscious) to 15 (fully awake).
  

• It tests the following three responses:  (1) eye, (2) verbal, and (3) motor, listed in order of increasing functional significance with regard to status (i.e. optimal eye response assigned lower score (best score = 4), followed by a best score of 5 for verbal response, and optimal motor function being scored at 6.

• The most common anatomical locations for ischemic stroke are in the internal capsule and the basal ganglia.
• Look for hypodensity (i.e. darkening which suggests edema) in these parts of the brain on CT when trying to locate areas of stroke.
• Acute stroke typically takes at least 3 hours to manifest in the form of edema on Head CT.  The larger the stroke, the quicker the abnormality is seen.

• Despite guidelines that recommend against opioid use as first-line treatment for migraine headaches,  meperidine (Demerol) is still administered in 36% of all migraine headache ED visits in the U.S.

• Meperidine's lack of efficacy, adverse effects such of seizure, and toxic metabolic accumulation all contribute to its use for migraine headaches being discouraged.

• A recent meta-analysis out of New York again supports the avoidance of using meperidine for migraine headaches, and instead, encourages clinicians to use anti-emetic and dihydroergotamine regimens.

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