There are many other motor findings in PD (Table 1), most of which are directly related to one of the cardinal signs. For example, the loss of facial expression (hypomimia, masked facies) and the bulbar symptoms (dysarthria, hypophonia, dysphagia, and sialorrhea) result from orofacial-laryngeal bradykinesia and rigidity (96). Respiratory difficulties result from a variety of mechanisms, including a restrictive component due to rigid respiratory muscles and levodopa-induced respiratory dyskinesia (97,98).
Of the various oculomotor problems characteristically seen in PD, the following are most common: impaired saccadic and smooth pursuit, limitation of upward gaze and convergence, oculogyric crises, spontaneous and reflex blepharospasm, apraxia of lid opening (involuntary levator inhibition), and apraxia of eyelid closure (99,100). Although supranuclear ophthalmoplegia is often used to differentiate PSP from PD, this oculomotor abnormality has also been described in otherwise typical parkinsonism (101).
Some patients exhibit the reemergence of primitive reflexes attributed to a breakdown of the frontal lobe inhibitory mechanisms normally present in infancy and early childhood, hence the term "release signs." The glabellar tap reflex, also known as Meyerson's sign, has often been associated with PD. Its diagnostic accuracy, however, has not been subjected to rigorous studies. We examined the glabel-lar reflex and the palmomental reflex in 100 subjects, which included patients with PD (n=41), PSP (n=12), MSA (n=7), and healthy, age-matched, controls (n=40). Although relatively sensitive signs of parkinsonian disorders, particularly PD, these primitive reflexes lack specificity, as they do not differentiate between the three most common parkinsonian disorders (102). In one study, 24 of 27 patients with asymmetric PD
exhibited mirror movements on the less affected side, the mechanism of which is unknown (103).
Was this article helpful?