To describe the clinical and unique radiological features of a patient with Anti-Hu-mediated subacute sensory neuronopathy (SSN) and co-existing stiff person syndrome (SPS).

Anti-Hu antibodies are associated with paraneoplastic syndromes, classically SSN.  We report a patient with a non-paraneoplastic anti-Hu SSN who had selective dorsal column changes on spine MRI. 

Case report.

In 2003, a 57-year-old man presented with body spasms, leg stiffness, and dysphagia. Initial work up demonstrated elevated serum antiGAD65 antibodies, CSF pleocytosis (11 WBCs;87% monocytes) and an unremarkable MRI of neuraxis, body CT, and electrophysiological studies. He improved with pulse steroids. Diagnosis of SPS was made and was put on Mycophenolate (MMF) and monthly IVIG with complete improvement.

In 2009, he developed impaired proprioception/vibration/sharp sensation(non-length dependent pattern), gait dysfunction, and diffuse hyporeflexia. Nerve conduction studies revealed absent sensory potentials in multiple nerves but normal motor potentials. He had positive anti-Hu(1:7080) and anti-amphiphysin antibodies(1:15360). Ati-GAD65 antibody was negative. Body PET was negative. MMF was increased, which lead to gait improvement .

In 2011, anti-Hu and anti-amphiphysin remained highly elevated. FDG-PET was again negative in 2014. On recent exam, he had severe pinprick/touch/vibration/proprioceptive loss in all extremities(upper>lower), vibratory sensory level at C3, hyporeflexia, and gait ataxia. MRI demonstrated a non-enhancing longitudinally extensive T2-hyperintese lesion(C2-T1) in the dorsal columns.

Chronic anti-Hu-mediated SSN is associated with dorsal root changes, resembling vitamin B12 deficiency.  This is likely caused by secondary degeneration following an initial immune-mediated injury to the dorsal root neurons. This correlates with prior autopsy studies in patients with anti-Hu autoimmunity. Because this process is time-dependent, it’s rarely seen on imaging as most patients with anti-Hu autoimmunity die from associated tumors. In our case, cancer was not found. Anti-Hu autoimmunity should be considered in the differential diagnosis of longitudinally extensive dorsal cord myelopathies.