Neurology Emergencies Flashcards
Define Neurology Emergencies
Provide some common categories or diagnosis
Life threatening or if not treated urgently patient will likely have a poor functional prognosis
Respiratory paralysis
Acute change in mental status
Myasthenia gravis crisis
Guillain-Barré Syndrome (Symptom onset within 4 weeks)
Stroke/Intracranial hemorrhage
Seizure
Syncope
Acute onset Headache and AMS
Guillain-Barré Syndrome
Antecedent events
Infection
Vaccine
Other Triggers
Acute inflammatory demyelinating polyneuropathy
Respiratory or gastrointestinal infection eg. cytomegalovirus, influenza, HIV, COVID-19, Zika virus
Vaccinations eg. Influenza (esp. H1N1), Meningococcal vaccination, recombinant zoster vaccination, adenovirus vector COVID-19 vaccines eg. Janssen/J&J, AstaZeneca
Other Triggers (Tumor necrosis factor-alpha antagonist therapy, tacrolimus and suramin, isotretinoin, immune checkpoint inhibitors)
Define Guillain-Barré Syndrome
Limb weakness
Cranial nerve and bulbar symptoms
- What percentage of patients require ventilatory support?
Deep tendon reflexes
Symmetrical and progressive (typically over 2 weeks) muscle weakness and absent/depressed deep tendon reflexes +/- sensory of dysautonomia
Limb weakness
The weakness is usually symmetric and starts in the legs, but begins in the arms or facial muscles in about 10 percent of patients. Most patients progress to weakness in both arms and legs by the nadir
Cranial nerve and bulbar symptoms
Facial nerve palsies occur in more than 50 percent
Oropharyngeal weakness eventually occurs in 50 percent
Cranial nerve symptoms including ophthalmoplegia are also diagnostic features of some variant forms of GBS
10-30% will need ventilatory support
Decreased or absent deep tendon reflexes in the arms or legs are found in approximately 90 percent of patients at presentation
Guillain-Barré Syndrome
Sensory involvement
Dysautonomia (think end organs and CNS)
- What is the associated risk of mortality?
Paresthesias in the hands and feet are reported by more than 80 percent of patients, but sensory abnormalities on examination are frequently mild.
Pain due to nerve root inflammation, typically located in the back and extremities, can also be a presenting feature and is reported during the acute phase by two-thirds of patients with all forms of GBS
Ileus (42 percent)
Hypertension (39 percent)
Hypotension (37 percent)
Fever (29 percent)
Tachycardia or bradycardia (27 percent)
Urinary retention (24 percent)
Mortality in patients with dysautonomia was 6 versus 0 percent in those without dysautonomia. Severe autonomic dysfunction has also been associated with sudden death
Forms of Guillain-Barré Syndrome (5)
- Acute inflammatory DEMYELINATING polyneuropathy (85-90% of GBS)
GBS Variants
2. Acute axonal neuropathies [Acute motor axonal neuropathy (AMAN) and Acute motor and sensory axonal neuropathy (AMSAN)]
- GQ1b syndromes [Miller Fisher syndrome (MFS) and Bickerstaff brainstem encephalitis (BBE)]
Acute motor axonal neuropathy - Immunological pathogenesis
IgG antibodies to the gangliosides GM1, GD1a, GalNac-GD1a, and GD1b, which are present in peripheral nerve axons
Acute motor and sensory axonal neuropathy
Detail findings of electrodiagnostic studies and Immnological pathogenesis
Electrodiagnostic studies on patients with AMSAN show severely reduced or absent CMAP and sensory nerve action potential (SNAP) amplitudes. Axon degeneration in these patients is demonstrated by extensive active denervation needle electrode electromyography (EMG) studies.
AMSAN is also associated with antiganglioside antibodies to GM1, GD1a, GalNac-GD1a, and GD1b
Define GQ1b syndromes and which Dx does it include (3)
Why does it have a predisposition to affect certain end organs?
Pathology?
Variant forms of GBS characterized by clinical features of impairment of eye movement (ophthalmoplegia) and ataxia rather than limb weakness are frequently associated with seropositivity to antibodies against GQ1b.
The GQ1b antibody is thought to have a direct effect on the neuromuscular junctions between cranial nerves and ocular muscles. The GQ1b ganglioside is a component of oculomotor nerve myelin
Miller-Fischer syndrome, Bickerstaff brainstem encephalitis, and pharyngeal-cervical-brachial (PCB) variants.
The pathology appears to be chiefly due to demyelination
Define Miller Fischer Syndrome
EDx studies
Ophthalmoplegia with ataxia and areflexia but about one-quarter of patients who present with MFS will develop some limb weakness
Incomplete forms include acute ophthalmoplegia without ataxia and acute ataxic neuropathy without ophthalmoplegia. Some patients with MFS develop fixed, dilated pupils.
Electrodiagnostic studies in patients with MFS may reveal reduced or absent sensory responses without slowing of sensory conduction velocities. Those with clinical weakness may show abnormalities on nerve conduction studies typical of AIDP, such as increased distal latencies or conduction block with temporal dispersion of motor responses.
Define Bickerstaff brainstem encephalitis
Encephalopathy with ophthalmoplegia and ataxia
Define Pharyngeal-cervical-brachial weakness
Acute weakness of the oropharyngeal, neck, and shoulder muscles with swallowing dysfunction
Patients with the PCB variant may also have facial weakness but may be distinguished from those with AIDP because leg strength and leg reflexes are usually
Rare variants of Guillain-Barré Syndrome (5)
Paraparesis, acute pandysautonomia, pure sensory Guillain-Barré Syndrome, facial diplegia and distal limb paresthesia, acute bulbar palsy.
Diagnosis of Guillain-Barré Syndrome
History and Physical Exam
Cytoalbuminologic dissociation - Low CSF leukocyte count and high CSF protein
Cerebrospinal fluid - elevated protein (45 to 200 mg/dL (0.45 to 2.0 g/L)) and normal to mildly elevated leukocyte count (usually <5 cells/mm3)
Recovery starting two to four weeks after progression halts
Imaging options for Guillain-Barré syndrome
For most patients with symptoms of GBS who are evaluated with diagnostic imaging, we obtain magnetic resonance imaging (MRI) of the brain and spine with contrast.
MRI of the brain and cervical spine imaging is typically performed for patients with bulbar weakness and/or quadriparesis
MRI of the thoracic and lumbar spine imaging is performed for those with lower extremity weakness to evaluate for transverse myelitis or another cause for myelopathy.
Details to focus on Neurological Exam for Guillain-Barré syndrome
Shoulder abductors, elbow flexors, wrist extensors, hip flexors, knee extensors, and foot dorsiflexors
Facial/bulbar/neck strength assessment in the facial muscles and the neck flexors and extensors
– Progressive weakness in these muscle groups indicates a worse prognosis and a greater possibility of the need for mechanical ventilation.
Indications for ICU level care in Guillain-Barré syndrome
Respiratory
Impending respiratory failure, severe or rapidly progressive weakness, or autonomic instability
ICU
Guillain-Barré syndrome - Respiratory
Objective findings
- imminent respiratory failure
- Rapid decline in respiratory function (>30 percent in 24 hours) who do not have overt signs of imminent respiratory failure.
- This setting provides monitoring to allow for an elective intubation if necessary and can decrease the need for emergent intubation
Clinical signs of respiratory failure include obvious:
- Shortness of breath while speaking or at rest
- Use of accessory muscles of breathing
- Inability to count to 15 in one breath
- Increased respiratory rate with tachycardia or abnormal arterial blood gases, and
5. FVC < 15 to 20 mL/kg or < 1L.
Respiratory rate sustained at >30 breaths/minute
- Oxygen saturation <92 percent
- FVC <20 mL/kg or reduction >30 percent from prior measurement
- NIF
- MEP <40 cm H20
- Acute hypercapnia with a PaCO2 >50 mmHg
* Bulbar dysfunction with swallowing impairment, inability to clear secretions, and other signs of muscle weakness may also indicate the need for ventilatory support
What clinical scoring tool can be used to help evaluate Guillain-Barré syndrome?
What physical examination is included?
Erasmus GBS Respiratory Insufficiency Score
Shoulder abduction
Elbow flexion
Wrist extension
Hip flexion
Knee extension
Ankle dorsiflexion
ICU
Guillain-Barré syndrome - Autonomic instability
Objective findings
Patients with cardiac arrhythmias or labile blood pressure indicative of autonomic dysfunction also warrant ICU admission
When to back off for Guillain-Barré syndrome
Less severely affected patients can be managed in intermediate care units, and mildly affected patients who are not in the acute (progressive) phase can be managed on the general ward unit.
However, continued monitoring of neurologic, respiratory, and hemodynamic status is necessary until patients are in the plateau phase (symptoms stable for >72 hours) since patients with GBS can deteriorate quickly.
What neuromuscular blocker agent should be avoided during intubation for Guillain-Barré syndrome?
Succinylcholine should be avoided to avoid the risk of inducing hyperkalemia
DVT PPx option for Guillain-Barré syndrome
Low molecular weight Heparin - Enoxaparin
Disease modifying therapy for GBS
Dose and duration
Immune globulin (IVIG) - 400 mg/kg q24hours x 5 days
Or
Therapeutic aphersis Plasma exchange (PLEX) - Based on desired end point such as clinical improvement or reduction in the level of the pathologic entity
- Five separate procedures over 7 to 10 days are required to remove 90 percent of the total initial body immunoglobulin burden
Define Myasthenic crisis (What contributes to it?) vs impending myasthenic crisis
Worsening of myasthenic weakness requiring intubation or noninvasive ventilation
While the respiratory failure is due to weakness of respiratory muscles, severe bulbar (oropharyngeal) muscle weakness often accompanies the respiratory muscle weakness, or may be the predominant feature in some patients.
vs
rapid clinical worsening of myasthenia gravis that, in the opinion of the treating clinician, could lead to crisis in the short term (days to weeks)
