Differential Diagnosis for Progressive Ataxia and Urine Retention in a 70-year-old Male with Normal Imaging

Single Most Likely Diagnosis

• Multiple System Atrophy (MSA): This is a neurodegenerative disorder characterized by progressive ataxia, autonomic dysfunction (such as urine retention), and parkinsonism. The normal imaging findings do not rule out MSA, as it often presents with non-specific or normal imaging in its early stages.

Other Likely Diagnoses

• Spinocerebellar Ataxia (SCA): A group of autosomal dominant disorders that cause progressive ataxia. Some types of SCA can also present with autonomic dysfunction, including urinary symptoms.
• Normal Pressure Hydrocephalus (NPH): Although imaging is reported as normal, NPH can sometimes present with subtle or missed findings on initial scans. It classically presents with the triad of gait disturbance, dementia, and urinary incontinence (which could initially be retention).
• Chronic Inflammatory Demyelinating Polyneuropathy (CIDP): An autoimmune disorder that can cause progressive weakness and ataxia, along with autonomic dysfunction.

Do Not Miss Diagnoses

• Spinal Cord Compression or Tumor: Even with normal initial imaging, spinal cord lesions can cause progressive ataxia and urinary retention. Repeat or more detailed imaging (e.g., MRI of the spine) might be necessary to rule out these conditions.
• Cauda Equina Syndrome: A condition where the nerves in the spinal canal are compressed, leading to neurological symptoms including ataxia and urinary retention. It requires urgent diagnosis and treatment.
• Vitamin B12 Deficiency: Can cause subacute combined degeneration of the spinal cord, leading to ataxia and urinary symptoms. It's easily treatable and thus important not to miss.

Rare Diagnoses

• Friedreich's Ataxia: An autosomal recessive genetic disorder that causes progressive ataxia, but it typically presents at a younger age.
• Ataxia-Telangiectasia: A rare genetic disorder that affects the nervous system, immune system, and other bodily systems, presenting with ataxia among other symptoms, usually at a young age.
• Paraneoplastic Cerebellar Degeneration: A rare condition associated with cancer, where the immune system attacks the cerebellum, causing ataxia. The presence of a tumor might not always be immediately apparent.