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).

References

Gordon, P. H., Cheng, B., Katz, I. B., Pinto, M., Hays, A. P., Mitsumoto, H., & Rowland, L. P. (2006). The natural history of primary lateral sclerosis. Neurology, 66(5), 647-653. doi: 10.1212/01.wnl.0000200962.94777.71

Kuipers-Upmeijer, J., de Jager, A., Hew, J., Snoek, J., & van Weerden, T. (2001). Primary lateral sclerosis: Clinical, neurophysiological, and magnetic resonance findings. Journal of Neurology Neurosurgery and Psychiatry, 71(5), 615-620. doi:10.1136/jnnp.71.5.615

Singer, M. A., Statland, J. M., Wolfe, G. I., & Barohn, R. J. (2007). Primary Lateral Sclerosis. Muscle & Nerve, 35(3), 291-302. doi: 10.1002/mus.20728

Statland, J. M., Barohn, R. J., Dimachkie, M. M., Floeter, M. K., & Mitsumoto, H. (2015). Primary lateral sclerosis. Neurologic Clinics, 33(4), 749-760. doi:10.1016/j.ncl.2015.07.007

Strong, M. J., & Gordon, P. H. (2005). Primary lateral sclerosis, hereditary spastic paraplegia and amyotrophic lateral sclerosis: Discrete entities or spectrum? Amyotrophic Lateral Sclerosis, 6(1), 8-16. doi:10.1080/14660820410021267