title: Primary lateral sclerosis mimicking atypical parkinsonism.
abstract: Primary lateral sclerosis (PLS), the upper motor neurone variant of motor neurone disease, is characterized by progressive spinal or bulbar spasticity with minimal motor weakness. Rarely, PLS may present with clinical features resembling parkinsonism resulting in occasional misdiagnosis as one of the atypical parkinsonian syndromes. Here we describe five patients initially referred with a diagnosis of levodopa-unresponsive atypical parkinsonism (n = 4) or primary progressive multiple sclerosis (n = 1), but subsequently found to have features consistent with PLS instead. Onset age varied from 49 to 67 years. Unilateral limb slowness or clumsiness was the initial complaint in four, and bulbar symptoms in one. Repeated finger/foot tapping was slow in all five, but without fatiguing or decrement. Spasticity with hyperreflexia, exaggerated jaw jerk and extensor plantar responses were eventually seen in all patients. Anterior horn cell involvement developed in three cases. Early gait disturbances resulting in falls were seen in all patients and none of them responded to dopaminergic medications. Two patients underwent dopamine transporter (DaT) SPECT scanning with normal results. Other features included emotional lability (n = 5) and cognitive impairment involving frontal subcortical systems (n = 1). In conclusion, these cases represent a subgroup of PLS patients in whom pyramidal slowness may be mistaken for akinesia, and spasticity misconstrued as rigidity, leading to an erroneous diagnosis of atypical parkinsonism. However, the absence of fatiguing and decrement on repeated finger/foot tapping should help to distinguish these patients from the true atypical parkinsonian syndromes.
authors: Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, London, United Kingdom.
authors: Ibrahim M
authors: IM
authors: Norlinah
authors: Kailash P
authors: KP
authors: Bhatia
authors: Karen
authors: K
authors: Ostergaard
authors: Robin
authors: R
authors: Howard
authors: Gennarina
authors: G
authors: Arabia
authors: Niall P
authors: NP
authors: Quinn
mesh_terms: D000368:Aged; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D016472:Motor Neuron Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging; D010300:Parkinson Disease / Q000503:physiopathology*; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins