Differential Diagnosis for Positive Romberg with Ataxia

The patient's presentation of a positive Romberg test along with ataxia, particularly noted when walking on heels, suggests a problem with proprioception (the sense of the relative position of one's own parts of the body) or cerebellar function, despite a normal cerebral exam. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Sensory Ataxia due to Peripheral Neuropathy: This condition affects the peripheral nerves, leading to a loss of proprioception. The positive Romberg sign and ataxia, especially when walking on heels (which requires precise proprioception), are consistent with sensory ataxia. Conditions like diabetes, vitamin B12 deficiency, or other causes of peripheral neuropathy could be underlying causes.

• Other Likely Diagnoses

  • Cerebellar Ataxia: Although the cerebral exam is normal, cerebellar pathology (such as cerebellar stroke, tumor, or degenerative conditions like spinocerebellar ataxia) could present with ataxia. The normal cerebral exam does not entirely rule out cerebellar involvement, as the cerebellum is part of the brainstem and not the cerebral hemispheres.
  • Vitamin B12 Deficiency: This can cause subacute combined degeneration of the spinal cord, leading to proprioceptive loss and ataxia. It's a treatable condition, making it an important consideration.
  • Tabes Dorsalis: A late manifestation of syphilis affecting the dorsal columns of the spinal cord, leading to loss of proprioception and ataxia.

• Do Not Miss Diagnoses

  • Spinal Cord Compression or Lesion: Conditions like spinal stenosis, herniated discs, or spinal tumors can compress the spinal cord, affecting proprioceptive pathways and leading to ataxia. Early diagnosis is crucial to prevent permanent damage.
  • Multiple Sclerosis: Although less common, multiple sclerosis can present with ataxia due to lesions in the cerebellum or spinal cord. A high index of suspicion is necessary, especially in younger patients.
  • Cauda Equina Syndrome: A serious condition where the nerves in the spinal canal are compressed, leading to sensory and motor deficits, including ataxia.

• Rare Diagnoses

  • Friedreich's Ataxia: An autosomal recessive inherited disease that causes progressive damage to the nervous system, resulting in ataxia among other symptoms.
  • Ataxia-Telangiectasia: A rare, inherited disorder affecting the nervous system, immune system, and other bodily systems, characterized by ataxia and telangiectasias.
  • Abetalipoproteinemia: A rare inherited disorder that affects fat absorption and leads to vitamin E deficiency, causing ataxia due to the degeneration of the sensory neurons.

Each of these diagnoses has a different set of implications for treatment and prognosis, highlighting the importance of a thorough diagnostic workup to determine the underlying cause of the patient's symptoms.