Nevertheless, the clinical signs (symptoms) presented by the patient, combined with neuropsychological tests, MRI brain imaging and oculomotor examination, strongly point the clinician towards a diagnosis of PSP.
In the early years of the disease, symptoms may be similar to those of Parkinson’s disease, but more suggestive signs make diagnosis highly likely. Specific criteria are oculomotor disturbances and fall-back due to postural instability (retropulsions).
Oculomotor symptoms are very often characterized by difficulty moving the eyes up or down, or following the eyes of a moving object. The upper eyelids can be raised and retracted, resulting in a particular facial with an expression of amazement or squinted eyes. Muscle contractures are also observed, especially at the neck, with difficulty flexing the neck and a rearward extension of the head (retro-pack).
The absence or non-permanence of resting tremors also differentiates PSP from Parkinson’s disease.
To date, 5 different forms of progressive supranuclear palsy have been identified, different by clinical signs presented by patients but due to identical brain lesions. They are:
- Classic PSP
- PSP-Parkinson (no falls or oculomotor problems)
- PSP-PAGF (predominance of movement and freezing difficulties)
- PSP-CBS (speech impairment, loss of balance, repeated falls)
- PSP-APNF (severe early and progressive language disorders)
In addition to clinical symptoms, the probable diagnosis of PSP is based on 4 types of examinations:
– Neuropsychological tests showing deficits in reasoning, judgment, attention, memory and interpretation of information received
– Morphological brain imaging to visualize neuronal loss (atrophy) in specific areas of the brain
– Functional brain imaging that provides an assessment of loss of function due to lesions especially in the frontal region or at the base nuclei.
– A record of eye movements that quantifies the loss of vertical mobility of the eyes.