David Baillot/UC San Diego Jacobs School of Engineering
Because of the logistics and invasive procedures involved, many people put off getting tested for Alzheimer’s and Parkinson’s diseases. Thanks to a new portable device, however, such testing could soon be performed non-invasively at just about any location.
Ordinarily, testing for neurodegenerative diseases such as Alzheimer’s and Parkinson’s requires patients to travel to a hospital or clinic where they undergo a spinal tap and MRI scan. Needless to say, not many people are enthusiastic about doing so, plus they may lack the physical mobility or means of transportation needed to make the trip.
Source: Portable device detects Alzheimer’s and Parkinson’s biomarkers on the spot
.
Critics:
Parkinson’s disease is the commonest form of parkinsonism and is also called idiopathic parkinsonism, meaning that it has no identifiable cause. The accumulation of a misfolded protein alpha-synuclein in the brain, and its spread throughout the brain makes Parkinson’s disease a neurodegenerative disease classed as a synucleinopathy, and more specifically as an alpha-synucleinopathy (αsynucleinopathy).
Other Parkinson-plus syndromes can have similar movement symptoms but have a variety of associated symptoms. Some of these are also synucleinopathies. Lewy body dementia involves motor symptoms with early onset of cognitive dysfunction and hallucinations which precede motor symptoms. Alternatively, multiple systems atrophy or MSA usually has early onset of autonomic dysfunction (such as orthostasis), and may have autonomic predominance, cerebellar symptom predominance, or Parkinsonian predominance.
Other Parkinson-plus syndromes involve tau, rather than alpha-synuclein. These include progressive supranuclear palsy (PSP) and corticobasal syndrome (CBS). PSP predominantly involves rigidity, early falls, bulbar symptoms, and vertical gaze restriction; it can be associated with frontotemporal dementia symptoms. CBS involves asymmetric parkinsonism, dystonia, alien limb, and myoclonic jerking.
These presentation timelines and associated symptoms can help differentiate these similar movement disorders from idiopathic Parkinson disease.The most recognizable symptoms are movement (motor) related, and include tremor, bradykinesia, rigidity, and shuffling/stooped gait.Non-motor symptoms, including autonomic dysfunction (dysautonomia), neuropsychiatric problems (mood, cognition, behavior or thought alterations), and sensory (especially altered sense of smell) and sleep difficulties may be present as well.
Patients may have non-motor symptoms that precede the onset of motor symptoms including constipation, anosmia, and REM Behavior Disorder. Generally, symptoms such as dementia, psychosis, orthostasis, and more severe falls occur later.Dysphagia can begin at any time during the course of Parkinson’s, and affects more than 80% of patients.
Four motor symptoms are considered as cardinal signs in PD: tremor, slowness of movement (bradykinesia), rigidity, and postural instability. The most common presenting sign is a coarse, slow tremor of the hand at rest, which disappears during voluntary movement of the affected arm and in the deeper stages of sleep. It typically appears in only one hand, eventually affecting both hands as the disease progresses.
Frequency of PD tremor is between 4–6 hertz (cycles per second). A common characteristic of tremor is pill-rolling, the tendency of the index finger and thumb to touch and perform together with a circular movement. The term derives from the similarity between the movement of people with PD and the early pharmaceutical technique of manually making pills. Bradykinesia is due to disturbances in motor planning of movement initiation, and associated with difficulties along the whole course of the movement process, from planning to initiation to execution of a movement.
Performance of sequential and simultaneous movement is impaired. Bradykinesia is the most handicapping symptom of Parkinson’s disease, presenting as difficulties with everyday tasks such as dressing, feeding, and bathing. It leads to particular difficulty in carrying out two independent motor activities at the same time, and can be made worse by emotional stress or concurrent illnesses. Paradoxically, people with PD can ride a bicycle or climb stairs more easily than walk on the level.
Although most physicians may readily notice bradykinesia, formal assessment requires persons to do repetitive movements with their fingers and feet. In parkinsonism, rigidity or hypokinesia can be uniform, known as lead-pipe rigidity, or ratcheted, known as cogwheel rigidity. The combination of tremor and increased tone is considered to be at the origin of cogwheel rigidity.
Rigidity may be associated with joint pain; such pain being a frequent initial manifestation of the disease. In early stages of PD, rigidity is asymmetrical and tends to affect the neck and shoulder muscles before the muscles of the face and extremities. With the progression of the disease, rigidity typically affects the whole body and reduces the ability to move. Postural instability is typical in the later stages of the disease, leading to impaired balance and frequent falls, and secondarily to bone fractures, loss of confidence, and reduced mobility.
Instability is absent in the initial stages, especially in younger people, especially before the development of bilateral symptoms. Up to 40% of people diagnosed with PD may experience falls, and around 10% may have falls weekly, with the number of falls being related to the severity of PD. Other recognized motor signs and symptoms include gait and posture disturbances such as festination (rapid shuffling steps and a forward-flexed posture when walking with no flexed arm swing).
Other common signs include freezing of gait (brief arrests when the feet seem to get stuck to the floor, especially on turning or changing direction), a slurred, monotonous, quiet voice, mask-like facial expression, and handwriting that gets smaller and smaller.
Leave a Reply