N7) Weakness and parasthesias in an immunosuppressed patient

Review the Learning Outcomes, Hx, PE and Labs, and begin the module with your Provisional Diagnosis. Keep hitting "Next" to move through the module.

Learning Outcomes

  1. Articulate your relationship with the consulting diagnostic radiologists in the evaluation of a patient with weakness.
  2. Review the DDx considerations in a patient with weakness.
  3. Identify the spectrum of imaging findings in appropriate modalities for evaluating a patient with weakness.


Physical Exam


Provisional Diagnosis

Select the Dx you believe is most appropriate
Considering the patient's history of immunosuppression, recent pneumonia, current fever, elevated white blood cell count and inflammatory markers, as well as the improvement of neurological symptoms after antibiotic treatment, the patient is likely suffering from multiple brain abscesses resulting from septic emboli from the lungs.
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Potential Acuity

What is your assessment of the likely acuity for this patient?

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The patient requires urgent workup and management.

First Imaging Study

What is the first imaging study you will order?

The best initial imaging modality for a suspected brain abscess is an MRI of the head. In this patient with "red flags" including fever, neurologic deficits, history of immunocompromise, and older age (>50 years), an MRI an appropriate initial imaging modality. It provides detailed and sensitive evaluation of the brain.
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Pertinent Imaging Observations

Click on the links below to view images from the study, and assess these key findings as best you can.

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Second Imaging Study

What is the next imaging study you will order?

A CTA of the head and neck could be considered to evaluate for mycotic aneurysms as a potential cause of the septic emboli. However, given the patient's known Nocardial pneumonia, this is less likely.
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What is your Diagnosis now that you have seen the imaging results?

In this patient, it is most likely that the brain abscesses have developed as a result of septic emboli originating from the Nocardial pneumonia.

Current Acuity

Initially, you selected and we suggested acuity.

Has your concern for this patient changed?

The patient requires a routine, but expedited workup, as the lesions are small, non-compressive, and the patient's symptoms are already improving with treatment for Nocardial pneumonia.

Assessment and Plan

Please provide your assessment and plan for this patient

The 55-year-old male patient, who is on immunosuppressive medications following a kidney transplant, has recently experienced neurological deficits while being treated for Nocardial pneumonia. Imaging studies reveal multiple small, non-compressive, peripherally enhancing lesions throughout the cerebrum, indicative of brain abscesses. Although a CTA of the head and neck could evaluate for mycotic aneurysms as a potential cause of septic emboli, it is less likely due to the patient's known Nocardial pneumonia. Given the improvement in symptoms with ongoing treatment, Nocardial brain abscesses are the most likely diagnosis. The patient should continue targeted antibiotic therapy with an antibiotic like trimethoprim-sulfamethoxazole (TMP-SMX) as a first-line lipophilic antibiotic that crosses the blood-brain-barrier, with adjustments based on sensitivity testing, and consider. Regular follow-ups, including serial MRI scans, are essential for monitoring the patient's progress.

Lessons Learned:
- CNS Nocardiosis, a rare bacterial infection primarily affecting immunocompromised individuals, often manifests as multiple small brain abscesses.
- Brain abscesses due to Nocardiosis typically arise as septic emboli resulting from pulmonary Nocardiosis dissemination, with patients initially presenting with pulmonary symptoms. Therefore, this diagnosis should be suspected in immunocompromised patients with known lung disease presenting with brain abscesses. However, some patients may present with primary brain lesions.
- Notable subtypes that spread to the brain include Nocardia beijingensis, farcinica, and asteroides, among others.
- Patients can present with single or multiple abscesses, generally characterized by thin, regular, enhancing walls, diffusion restriction, and significant perilesional edema.
- While the diagnosis of CNS Nocardiosis can often be made presumptively, neurosurgical biopsy might be necessary in some cases. Minimally invasive techniques are increasingly employed to ensure patient safety.

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