Primary Lateral Sclerosis

Differential Diagnoses

(Statland et al, 2015); (Kuipers-Upmeijer et al, 2001); (Strong & Gordon, 2005)

As PLS is an upper motor neuron issue, there are several potential differential diagnosis. The 2 most likely upper motor neuron diseases that is associated with PLS are …

• Amyotrophic lateral sclerosis (Statland et al, 2015); (Strong & Gordon, 2005)

        - ALS presents with lower and/or upper motor deficits and has fast(er) progression; PLS is slower progression and typically only affects                upper motor neurons.
        - ALS is more commonly associated with stiffness then PLS (47% vs 4%)
        - Both ALS and PLS can be assoicated with cognitive issues but is not present in its ‘uncomplicated’ forms (Strong & Gordon, 2005).

• Hereditary spastic paraplegias (Strong & Gordon, 2005)

         - HSP has spasticity of the lower limbs; PLS is associated with spasticity as well and slight weakness but spasticity can affect                              speech (spastic dysarthria)
         - Complicated cases of HSP can result in dementia & mental retardation which may mimic cognitive issues possibly present in                              complicated cases of PLS.

Other potential, but less specific, differential considerations include (Statland et al, 2015)…

• Structural lesions, especially related to the spine (eg. cervical spondylmyelopathy)
• Infection (eg. HIV, syphilis)
• Demyelinating disease (eg. mutliple sclerosis)
• Metabolic / toxic (eg. vitamin E deficiency)
• Neurodegenerative (eg. Parkinsons and parkinson's-plus syndromes)

Special care must be taken when diagnosing as PLS can be misdiagnosed as the above examples, and many more (Kuipers-Upmeijer et al, 2001).