Degeneration of cells in pars compacta of substantia nigra
Symptoms appear after 50% of dopaminergic neurons and 80% of striatal dopamine is depleted
Clinical picture
Asymmetry
Resting tremor
Good response to dopamine replacement therapy
Fatigue
Depression
Lack of coordination
Axial posture progressively flexed
Decreased swallowing, excess saliva and drooling
Constipation
Sweating abnormalities
Sexual dysfunction
Sleep disturbances
Seborrheic dermatitis
Imaging
Swallow tail sign: Normally nigrosome (N1) has low iron content in substantia nigra pars compacta. Nigrosome is surrounded by iron rich pars reticulata demonstrating an intrinsic contrast. Loss of this contrast due to mineralization of nigrosome is seen in Parkinson’s
Treatment
Mainstay is levodopa
Intractable cases – deep brain stimulators used. DBS seen in chest radiographs with leads ascending with tips in the region of subthalamic nuclei.