<prompt> Which of the following is not a cause of absent ankle jerks and up-going plantars?Freidreichs ataxiaB12 deficiencyMSCord compression  <response>: Causes of absent ankle jerks and upgoing plantars is a common question as it implies both upper and lower motor neuron involvement. The more common single causes include cord compression involving both the cord UMN and nerve ganglia roots LMN as well as subacute combined degeneration of the cord. Other more common causes include the presence of more than one pathology, e.g. stroke UMN with superimposed peripheral neuropathy LMN usually in a diabetic patient. In Friedrichs ataxia, both cord and peripheral nerve involvement accompany cerebellar degeneration. These patients also have sensory loss, pescavus and may have complications such as diabetes and hypertrophic cardiomyopathy. Multiple sclerosis may cause a mixture of pyramidal signs UMN, sensory loss dorsal columns and ataxia cerebellum, but will never involve the LMN. 