Differential Diagnosis of Symmetrical Posterior Putaminal Hyperintensity
Single Most Likely Diagnosis
- Hypertensive Encephalopathy: This condition is characterized by symmetrical posterior putaminal hyperintensity on MRI due to vasogenic edema, often seen in the setting of severely elevated blood pressure. The posterior circulation's susceptibility to hypertension makes this a common site for such changes.
Other Likely Diagnoses
- Toxins/Metabolic Disorders: Certain toxins (e.g., methanol, carbon monoxide) and metabolic disorders (e.g., Wilson's disease, mitochondrial disorders) can cause symmetrical changes in the putamen due to their toxic effects on the brain or due to metabolic derangements affecting the basal ganglia.
- Infections: Viral encephalitis, such as Japanese encephalitis, can present with symmetrical basal ganglia involvement, including the putamen, due to the virus's predilection for these areas.
- Autoimmune and Inflammatory Conditions: Conditions like multiple sclerosis, systemic lupus erythematosus (SLE), and antiphospholipid syndrome can occasionally present with basal ganglia lesions, including the putamen, though symmetry might be less common.
Do Not Miss Diagnoses
- Methanol Poisoning: Although less common, methanol poisoning can cause bilateral putaminal necrosis and is crucial to identify early due to its potential for severe visual and neurological sequelae if not promptly treated with appropriate antidotes.
- Wilson's Disease: An inherited disorder of copper metabolism, Wilson's disease can present with neurological symptoms and bilateral basal ganglia abnormalities, including the putamen. Early diagnosis is critical for preventing further neurological deterioration.
- Creutzfeldt-Jakob Disease: A rare, fatal neurodegenerative disorder that can present with symmetrical basal ganglia hyperintensity on MRI. Given its rapid progression and fatal outcome, it's essential not to miss this diagnosis.
Rare Diagnoses
- Leigh Syndrome: A rare inherited disorder that affects the central nervous system and can present with symmetrical lesions in the basal ganglia, including the putamen, due to defects in mitochondrial energy production.
- Pantothenate Kinase-Associated Neurodegeneration (PKAN): A form of neurodegeneration with brain iron accumulation (NBIA) characterized by iron accumulation in the basal ganglia, leading to symmetrical changes, including in the putamen.
- Fahr's Disease: A rare, inherited disorder characterized by abnormal calcification of the brain, including the basal ganglia, which can present with symmetrical putaminal hyperintensity on certain MRI sequences.