The head CT scan shows no obvious pathology, such as hemorrhage, midline shift, or cerebral contusion. No old infarct pattern is noted.
No fracture or subluxation is seen on the cervical spine series.
What further steps will you take to evaluate this patient?
Because his focal neurologic deficit and mental state are stable, an outpatient MRI scan and Doppler duplex study of the carotid arteries are scheduled. MRI provides greater detail about the parenchymal central nervous tissue (for example, it can show a resolving infarct). The Doppler duplex study was ordered to evaluate the carotid arteries as a possible site of origin for a cerebral embolus resulting from arteriosclerotic disease.
Before the patient is discharged, a nurse notes that his temperature is 38.6oC (101.4oF). A lumbar puncture is ordered to rule out meningitis because of the presence of fever, confusion, arm weakness, and headache. The cerebrospinal fluid (CSF) is hazy with a white blood cell count of 1140/µL, all of which are neutrophils. CSF glucose level is 45 mg/dL, and protein level is high (93 mg/dL). Gram staining of CSF shows no bacteria or fungi. The patient is given ceftriaxone(Drug information on ceftriaxone), 2 g in an intravenous piggyback and 1 g q12h, for presumed bacterial meningitis, and he is admitted to the ICU.
Spinal fluid and blood cultures are both positive for Enterococcus faecalis, and his antibiotic regimen is switched to ampicillin(Drug information on ampicillin), 2 g q4h for 6 weeks, and gentamicin(Drug information on gentamicin), 3 mg/kg/d in divided doses for 2 weeks.
What is your next step for this patient?
An MRI scan of the brain is ordered to determine the cause of the patient's continued left-sided weakness (Figure 1). The scan shows multiple small lesions of uncertain origin within the right parietal lobe, basal ganglia, and temporal lobe. The scan also reveals a focal area of cerebritis or a small parenchymal contusion with minimal increased signal within the right basal ganglia on the T1- weighted image, which suggests petechial hemorrhage.
What does the unilateral location of the lesions suggest-and how will you proceed to evaluate this finding?
The clustering of the lesions on the right side of the brain suggests vascular emboli. Of note, the admitting physician detected a significant heart murmur when she examined the patient in the quiet of his hospital room. An echocardiogram is performed to evaluate the heart as a potential source of repeated embolization (Figure 2).
The study shows vegetation that adheres to the mitral valve. Severe mitral regurgitation, prominent thickening of the mitral valve leaflet, and mild pulmonic regurgitation are evident. No obvious intracavitary mass, thrombus, or significant pericardial effusion is present. The dynamic study shows grossly normal left ventricular function and an ejection fraction of 55%. Based on the results of the echocardiogram and the growth of E faecalis on the blood culture, infective endocarditis is diagnosed.
One week later, a second MRI scan shows a similar pattern of rightsided lesions (Figure 3). No new lesions are detected. An area of increased signal intensity in the right basal ganglia is compatible with a diagnosis of septic embolism or infarction.
On the 10th hospital day, the patient is transferred to the rehabilitation department for gait training and speech therapy. The antibiotic regimen is discontinued after 42 days, at which time the blood culture shows no bacterial growth. The patient's neurologic deficits are steadily abating.
IMPLICATIONS FOR PRACTICE
This case demonstrates the convoluted course to diagnosis that sometimes confronts us. The sequence of presumptive diagnoses moved from stroke to motor vehicle accident with possible concussive head injury, to bacterial meningitis, to unilateral CNS lesions that were attributable to bacterial endocarditis.Several teaching points warrant emphasis:
- First, a complete set of vital signs, including temperature, is necessary in all ED patients, especially those whose clinical presentation involves CNS or infectious disease. The key finding in this patient was the discovery of his fever before discharge.
- Fever in the setting of altered mental status or a focal neurologic finding mandates lumbar puncture. In this patient, the procedure disclosed the cause of the acute symptoms.
- If a head CT scan is normal, an MRI scan of the brain can more completely elucidate the origin of neurologic deficits. Here, MRI demonstrated the unilateral lesions, which suggested a vascular cause.
- Finally, the echocardiogram revealed the mitral valve vegetations.