Pseudoathetosis is characterized by slow, involuntary, writhing movements. We report a unique case of NMO without AQP4 antibody presenting with pseudoathetosis at onset

A 44 year old woman presented with three days of numbness and weakness in her right arm and leg associated with slow, involuntary movements in her right hand making it difficult to perform fine motor tasks. These movements worsened when she closed her eyes.

Physical exam revealed increased tone in her right upper extremity with distal weakness, pathologically brisk reflexes, impaired pin prick and vibration in right sided extremities and impaired joint position sense in the right hand.

CSF studies revealed 7 oligoclonal bands and a negative serum AQP4 antibody. MRI revealed T2/FLAIR hyperintense signal in the posterior central pons and posterior cervical spinal cord at C2. She received a 5 day course of IV steroids with improvement in her symptoms.

Spinal lesions involving the posterior columns have been reported in association with syringomyelia, cervical disc extrusion, infarction, tumors, leprosy, vitamin B12 deficiency, multiple sclerosis and a previous case of NMO. Our case illustrates that a proprioceptive sensory deficit originating in the cervical cord can cause pseudathetosis in a deafferented hand. It is important to consider LETM from NMO spectrum disease as a cause for this clinical phenomenon. This appears to be the first case of NMO without AQP4 antibody, meeting core clinical and radiological characteristics, presenting with pseudoathetosis. Our patient improved with steroids in the acute phase and provoked consideration for disease modifying treatment