Should a patient with suspected central nervous system infection be referred to the ER instead of just undergoing an outpatient CT scan?

From the Guidelines

Yes, a patient with suspected central nervous system (CNS) infection should be referred to the emergency room rather than just undergoing an outpatient CT scan. CNS infections such as meningitis and encephalitis are medical emergencies that require immediate evaluation, diagnosis, and treatment to prevent serious complications including permanent neurological damage or death. In the ER, patients can receive prompt lumbar puncture (LP) to analyze cerebrospinal fluid, which is the gold standard for diagnosing CNS infections 1. While CT scans may be performed before LP to rule out increased intracranial pressure, they alone cannot diagnose most CNS infections. The ER setting allows for rapid initiation of empiric antimicrobial therapy, which typically includes broad-spectrum antibiotics like ceftriaxone (2g IV every 12 hours), vancomycin (15-20 mg/kg IV every 8-12 hours), and acyclovir (10 mg/kg IV every 8 hours) while awaiting culture results. Delays in treatment significantly increase mortality and morbidity rates. Additionally, patients with CNS infections often require close monitoring for neurological deterioration, seizures, increased intracranial pressure, and other complications that can only be properly managed in an inpatient setting.

Some key points to consider in the management of suspected CNS infections include:

• The importance of prompt LP to confirm the diagnosis and guide treatment 1
• The role of CT scans in ruling out increased intracranial pressure before LP, but not as a replacement for LP 1
• The need for empiric antimicrobial therapy, including broad-spectrum antibiotics and antivirals, while awaiting culture results 1
• The importance of close monitoring for neurological complications and other potential issues in an inpatient setting 1

It's also important to note that clinical assessment rather than CT scanning should be used to determine the safety of performing an LP, and that patients with suspected CNS infections should be referred to hospital for further evaluation and consideration of a lumbar puncture 1. In patients with suspected encephalitis, an early CT scan has two clear roles: suggesting the diagnosis of viral encephalitis and indicating an alternative diagnosis 1.

The most recent and highest quality study, 1, published in 2016, provides guidelines for the diagnosis and management of acute meningitis and meningococcal sepsis in immunocompetent adults, which can be applied to patients with suspected CNS infections. These guidelines emphasize the importance of prompt referral to hospital and rapid initiation of empiric antimicrobial therapy.

Overall, the evidence suggests that patients with suspected CNS infections should be referred to the emergency room for prompt evaluation, diagnosis, and treatment to prevent serious complications and improve outcomes.

From the Research

Patient Referral to the ER

The decision to refer a patient with suspected central nervous system infection to the ER instead of just undergoing an outpatient CT scan depends on several factors.

• The patient's condition and symptoms should be evaluated to determine the severity of the suspected infection.
• According to 2, urgent indications for lumbar puncture include suspected central nervous system infection or subarachnoid hemorrhage, which may require immediate attention in an ER setting.
• Additionally, 3 highlights the importance of cerebrospinal fluid (CSF) analysis in diagnosing CNS infections, which may not be feasible in an outpatient setting.

Considerations for Referral

When considering referral to the ER, the following points should be taken into account:

• The potential for bacterial meningitis, which has a high mortality rate and requires prompt treatment, as noted in 2.
• The possibility of other conditions that may mimic CNS infection, such as leptomeningeal carcinomatosis, which has a poor prognosis and requires large-volume CSF cytology for diagnosis, as mentioned in 2.
• The need for adjunctive tests, such as latex agglutination, immunological assays, and molecular reactions, which may be necessary to differentiate between infections caused by distinct groups of pathogens, as discussed in 3.

ER Referral Criteria

Based on the available evidence, referral to the ER may be warranted if the patient:

• Presents with severe symptoms, such as headache, fever, or confusion, which may indicate a life-threatening condition, as suggested by 2.
• Has a history of immunocompromised status, which may increase the risk of opportunistic infections, as noted in 2.
• Requires immediate lumbar puncture or other diagnostic procedures that cannot be performed in an outpatient setting, as implied by 3.