A 51-year-old man came to the hospital confused and having trouble remembering things, which doctors initially thought was a brain infection. However, advanced brain imaging revealed he actually had a small stroke in a deep part of his brain called the thalamus. This case shows how tricky it can be to diagnose sudden confusion, since a stroke can look similar to an infection. The patient improved over time with stroke treatment, though some memory problems lingered. This story reminds doctors to use advanced imaging early when patients suddenly become confused, to make sure they catch strokes that might otherwise be missed.

The Quick Take

  • What they studied: How a stroke in the brain’s thalamus (a small but important area deep in the brain) can look exactly like a brain infection, making it hard for doctors to diagnose correctly.
  • Who participated: One 51-year-old man who suddenly became confused and had memory problems without fever, headache, or other typical signs of infection.
  • Key finding: Brain imaging (MRI) showed the patient had a stroke in the left anterior thalamus, not an infection. His confusion improved within days, but memory problems took longer to recover.
  • What it means for you: If you or someone you know suddenly becomes confused without obvious symptoms, it’s important to get advanced brain imaging (like an MRI) quickly. What looks like one problem might actually be something different that needs different treatment.

The Research Details

This is a case report, which means doctors documented the medical story of one patient in detail. The patient arrived at the hospital confused and unable to remember familiar names. Doctors initially suspected encephalitis (brain infection) based on his symptoms and started him on antibiotics and vitamin supplements. However, when his condition didn’t improve as expected and memory problems persisted, doctors ordered an MRI scan. The MRI revealed a stroke in the thalamus, a walnut-sized structure deep in the brain that controls memory and consciousness. Once doctors identified the real problem, they switched treatment to stroke medications (blood thinners and cholesterol drugs).

This case is important because it shows how easily doctors can misdiagnose sudden confusion. A stroke in certain brain areas can produce symptoms almost identical to a brain infection, but the treatments are completely different. Using the wrong treatment can delay proper care and cause additional harm. This case demonstrates why advanced imaging should be done early when patients present with sudden confusion, even if initial tests seem normal.

This is a single case report, which is the lowest level of scientific evidence. It documents one patient’s experience in detail but cannot prove that this happens to many people or establish how common this problem is. However, case reports are valuable for alerting doctors to diagnostic possibilities they might otherwise miss. The detailed documentation and follow-up imaging make this a well-documented case.

What the Results Show

The patient presented with sudden confusion and memory loss without fever, headache, or other typical infection signs. Initial blood tests showed low vitamin B12 and D, elevated blood sugar markers, and high homocysteine levels. A CT scan of the brain appeared normal. Doctors started treatment for suspected brain infection with acyclovir (an antiviral medication) and vitamin supplements. By day four, the confusion improved significantly, but memory problems remained. An MRI scan performed later revealed a small stroke in the left anterior thalamus—a deep brain structure crucial for memory and awareness. After this discovery, doctors switched the patient to stroke treatment with blood thinners and cholesterol medication. The patient experienced a complication from the acyclovir (kidney injury), which improved after stopping the medication and receiving fluids. At discharge, confusion had resolved but memory issues persisted. Three months later, the patient showed significant cognitive improvement, though concentration remained somewhat reduced.

The patient developed acute kidney injury (stage 3) as a side effect of acyclovir treatment, which is a known but uncommon complication. This kidney problem resolved completely once the medication was stopped and the patient received intravenous fluids. The patient’s low vitamin B12 and D levels, along with elevated homocysteine, may have contributed to the stroke risk. These metabolic abnormalities were noted but not directly treated during the hospital stay. The patient’s elevated blood sugar markers (HbA1c) suggested uncontrolled diabetes, another stroke risk factor.

Thalamic strokes are known to cause memory and cognitive problems, but they are sometimes missed because they don’t always produce the obvious weakness or numbness associated with larger strokes. This case aligns with medical literature showing that strokes in deep brain structures can mimic infections or other conditions. The diagnostic confusion between stroke and encephalitis has been documented before, highlighting an ongoing challenge in emergency medicine. The patient’s presentation was unusual because he had no fever or headache, which are common with infections but not always present with strokes.

This is a single case report involving one patient, so the findings cannot be generalized to many people. We don’t know how often this type of misdiagnosis occurs or whether the patient’s specific combination of symptoms and risk factors is common. The case doesn’t include information about whether the patient had any previous strokes or brain problems. We also don’t have detailed information about the patient’s long-term recovery beyond three months. The kidney injury from acyclovir may have been influenced by other factors not fully documented. Finally, this case cannot prove that early MRI imaging would prevent all such misdiagnoses, though it suggests it would help.

The Bottom Line

If you suddenly become confused without obvious cause, seek emergency medical care immediately. Ask for advanced brain imaging (MRI) if initial CT scans are normal, especially if confusion persists. If you have risk factors for stroke (high blood pressure, diabetes, high cholesterol, or family history), discuss stroke prevention with your doctor. Maintain healthy vitamin B12 and D levels, manage blood sugar, and control cholesterol. These recommendations are based on this single case but align with general stroke prevention guidelines.

This case is most relevant to emergency room doctors and neurologists who need to recognize that strokes can mimic infections. Patients with sudden confusion should care about this because it emphasizes the importance of thorough evaluation. People with stroke risk factors (diabetes, high blood pressure, high cholesterol, or family history of stroke) should be particularly aware. This case is less directly relevant to people without these risk factors, though sudden confusion always warrants medical evaluation.

In this case, confusion improved within days of starting treatment, but complete recovery took much longer. Memory problems were still present at discharge but showed significant improvement by three months. Full cognitive recovery may take even longer. If you experience similar symptoms, improvement typically begins within days to weeks, but complete recovery can take months. Individual recovery varies greatly depending on the stroke’s location and size.

Want to Apply This Research?

  • Track cognitive symptoms daily: rate your memory (1-10), concentration ability (1-10), and any confusion episodes. Note any new symptoms like eye drooping, weakness, or speech difficulty. Log these in a health app with timestamps to share with your doctor.
  • If you have stroke risk factors, use the app to monitor and log daily: blood pressure readings, blood sugar levels (if diabetic), medications taken, and any neurological symptoms. Set reminders for medication adherence and doctor appointments. Track lifestyle changes like exercise minutes and dietary choices.
  • For long-term tracking, maintain a monthly cognitive check-in noting memory quality, concentration, and any persistent issues. If you’ve had a stroke, track recovery milestones and report significant changes to your healthcare provider. Use the app to maintain a medication list and stroke risk factor log for regular review with your doctor.

This case report describes one patient’s experience and should not be used for self-diagnosis. Sudden confusion, memory loss, or neurological symptoms require immediate medical evaluation by a healthcare professional. If you experience sudden confusion, difficulty speaking, weakness, numbness, or vision changes, call emergency services immediately. This information is educational and does not replace professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider about your specific symptoms and medical situation.