Brain Diseases and Disorders

11

fine movements, slowing down or slowing down of all movements, especially

walking, bending the body forward. These symptoms start insidiously and

progress slowly. A decrease in the sense of smell or shoulder pain may be one

of the first symptoms that go unnoticed. Over time, rigidity and bradykinesia

become evident and postural changes begin to occur. The patient’s mobility

gradually decreases as a result of decreased trunk rotation, arm swing during

walking, disappearance of spontaneous facial expressions, and increasing diffi-

culty initiating movement [60]. Another symptom is a form of freezing akinesia

known as a motor block, which is characterized by an abrupt, transient (less

than 10 seconds) immobility, primarily affecting the legs when walking. This

causes anxiety when the patient first starts to walk and makes it difficult to

move quickly when turning, crossing, or getting through tight spaces, which

can lead to falls.

Bradykinesia is the most common sign of the diseases affecting the basal

ganglia. It is characterized by trouble with movement-based activities includ-

ing coordination, purposeful movement initiation, direction changes, halting,

switching between movements, and simultaneous performance of two move-

ments. Activities and reaction times generally slow down, particularly in the

case of handling the sophisticated technologies. The clinical signs of bradyki-

nesia includes spontaneous cessation of movement, dribbling from the mouth

due to difficulties in swallowing, monotone and hypokinetic dysarthria, loss

of facial expression, decreased blinking, and decreased arm swing while walk-

ing. It can be easily detected by rapid, repetitive, and alternating movements

of the extremities in neurological examination. The degree of bradykinesia is

linked to a shortfall in dopamine and is considered to be the consequence of a

reduction in the dopaminergic activity leading to a decrease in activation of

the motor cortex, premotor cortex, and supplementary motor cortex [61].

The term “rigidity” describes the rise in muscular tone due to simultaneous

antagonist and agonist muscle contractions. The voluntary movement of the

opposing limb, commonly referred to as the “froment maneuver,” enhances

rigidity; this strengthening effect is crucial for exposing moderate rigidity

[62]. Postural instability is a condition that develops after other PD signs and

symptoms. It is the weakening or loss of postural reflexes, which ordinarily

automatically maintain the body position taken while standing or sitting in

healthy individuals. In contrast, patients struggle to get up from their sit-

ting positions without assistance due to postural instability. PD patients fre-

quently experience balance issues, falls, and especially backward falls. Postural

instability is also closely linked to other parkinsonian symptoms, orthostatic

hypotension, age-related sensory alterations, and kinesthetic impairments in

the control of vestibular, proprioceptive, and visual stimulations. The flexion

posture, bradykinesia, tremor, and stiffness associated with PD impede the

development of balance techniques and increases reaction times [63].

As PD symptoms are based on the lack of dopamine, for almost 40 years,

the best treatment for PD has been levodopa combined with peripheral decar-

boxylase inhibitors (carbidopa, benserazide) to prevent levodopa from being