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Contrast Enhancement and FLAIR signal along a Deep Brain Stimulation Electrode: 2 Cases
When wounds are benign, diagnosis of a DBS electrode infection and associated intra-parenchymal infection can be challenging. Only a couple such cases exist in literature. Since infections of the central nervous system can be life threatening, prompt diagnosis is necessary to prevent neurological injury. Employed within the appropriate context, MRI of the brain, as well as laboratory data and clinical presentation, may help guide diagnosis.
Case 1: A 55-year-old male with bilateral DBS electrodes and generators (49 days from last procedure), who presented with confusion and fever. Pertinent positive lab was WBC 20.5K. MRI of the brain showed edema with enhancement along the right DBS electrode. Wound exploration revealed gross purulence in the subgaleal space. The entire system was removed; cultures from subgaleal space revealed Propionibacterium acnes; cultures from electrode were negative. Patient was sent home on antibiotics.
Case 2: A 68-year-old male with a right DBS electrode (11 days from placement), who presented after an unwitnessed fall, followed by confusion and amnesia. Pertinent labs were negative. MRI of the brain showed edema with enhancement along the DBS electrode. Wound exploration revealed no infection. The DBS system was left in place; final cultures were negative; no antibiotics were prescribed. Repeat MRI showed resolving FLAIR signal and contrast enhancement.
Conclusions: Contrast enhancement, T2 FLAIR, and DWI are influenced by postoperative changes. Caution is stressed regarding dependence on these features for acute diagnosis of infection and indication for electrode removal. Timing of the imaging after surgery must be considered. Other factors, such as systemic signs and abnormal laboratory data, should be evaluated. Based on these guidelines, retrospectively, the patient in Case 2 should not have been rushed for a wound exploration; close observation with serial imaging and laboratory data may have prevented an unnecessary procedure.