Prehospital Academy Lesson 18.6
Neurologic Emergencies: Infectious Diseases and Cranial Nerve Disorders
This lesson continues our neurology series by examining neurologic infectious diseases and cranial nerve disorders. While less common than stroke or seizures, these conditions can present with symptoms that mimic more frequent emergencies. A thorough history and assessment are critical for EMTs to differentiate these conditions and provide appropriate supportive care.
Cranial Nerve Disorders
The twelve cranial nerves originate from the base of the brain and innervate the head and facial regions. Disorders of these nerves can produce a variety of symptoms, some of which can be mistaken for a stroke.
Bell's Palsy: A common cranial nerve disorder affecting the facial nerve (Cranial Nerve VII). It causes a sudden onset of unilateral facial paralysis, including drooping of the eyelid and corner of the mouth. A key differentiating factor from a stroke is that Bell's Palsy often affects the entire side of the face, including the forehead, whereas a stroke typically spares the forehead muscles. Obtaining a thorough history is crucial.
Vertigo: A sensation of spinning or dizziness, often caused by a disorder of the inner ear or the vestibulocochlear nerve (Cranial Nerve VIII). While often benign, it can be a symptom of a more serious underlying issue. Assessment may include observing for nystagmus (involuntary eye movements). Complications include nausea and vomiting.
Neurologic Infectious Diseases
Infections can affect the central nervous system, leading to inflammation and potentially severe neurological deficits. EMTs should maintain a high index of suspicion for infectious causes in patients presenting with fever, headache, and altered mental status, and should always take appropriate standard precautions.
Meningitis
Pathophysiology: Inflammation of the meninges, the protective membranes covering the brain and spinal cord. It can be caused by bacteria, viruses, or fungi.
Signs and Symptoms: Fever, severe headache, nuchal rigidity (stiff neck), photophobia (sensitivity to light), and altered mental status. A purpuric rash may be present in cases of meningococcal meningitis.
Management: Primarily supportive care, including airway management and oxygenation. Rapid transport is essential. Bacterial meningitis is a medical emergency that can be fatal if not treated promptly with antibiotics.
Encephalitis
Pathophysiology: Inflammation of the brain tissue itself, most commonly caused by a viral infection.
Signs and Symptoms: Similar to meningitis, but often with more profound neurological deficits such as seizures, personality changes, and paralysis.
Management: Supportive care, with a focus on managing life-threatening complications like seizures and airway compromise.
Assessment and Management Principles
The prehospital care for these conditions is largely supportive and focuses on identifying life threats.
Assessment:
Primary Assessment (ABCs): Ensure a patent airway, adequate breathing, and circulation. Patients with altered mental status are at high risk for airway compromise.
History (SAMPLE): A thorough history is critical. Ask about recent travel, illness, fever, headache, or a history of similar symptoms.
Neurological Exam: Assess level of consciousness (AVPU), pupil response, and gross motor function. While a full cranial nerve exam is not typically performed by EMTs, noting facial symmetry and eye movements is important.
Vital Signs: Monitor for fever, tachycardia, and changes in blood pressure or respiratory pattern.
Management:
Standard Precautions: Use appropriate personal protective equipment (PPE), including a mask, if an infectious disease is suspected.
Supportive Care: Manage the ABCs. Provide oxygen as needed, and be prepared to assist ventilations or suction the airway.
Symptom Management: For patients with vertigo and nausea, placing them in a position of comfort and providing an emesis basin can be helpful.
Rapid Transport: Transport to an appropriate facility is crucial, especially for suspected meningitis or encephalitis. Provide pre-arrival notification to the receiving hospital.
Critical Thinking Questions
A patient presents with sudden-onset left-sided facial droop but can still wrinkle their forehead. Why is this finding more indicative of a stroke than Bell's Palsy?
You are assessing a patient with a severe headache, fever, and a stiff neck. What neurologic infectious disease should you have a high index of suspicion for, and what specific standard precautions should you take?
Describe how you would perform a basic field assessment for vertigo. What associated symptoms might you expect the patient to complain of?
Explain why a thorough patient history is essential when you suspect a cranial nerve disorder that mimics the signs of a stroke. What key questions would you ask?
A patient with suspected meningitis becomes unresponsive. Describe your immediate management priorities.