word of the day - parkinson disease (PD)

Parkinson disease (PD) is one of the most common
neurologic disorders, affecting approximately 1% of
individuals older than 60 years and causing progressive
disability that can be slowed, but not halted, by treatment.

The 2 major neuropathologic findings in Parkinson disease
are loss of pigmented dopaminergic neurons of the
substantia nigra pars compacta and the presence of Lewy
bodies and Lewy neurites. See the images below.
Lewy bodies are intracytoplasmic eosinophilic inclusions,
often with halos, that are easily seen in pigmented neurons,
as shown in this histologic slide. They contain polymerized
alpha-synuclein; therefore, Parkinson disease is a
synucleinopathy.


Signs and symptoms
Initial clinical symptoms of Parkinson disease include the
following:
Tremor
Subtle decrease in dexterity
Decreased arm swing on the first-involved side
Soft voice
Decreased facial expression
Sleep disturbances
Rapid eye movement (REM) behavior disorder (RBD; a
loss of normal atonia during REM sleep)
Decreased sense of smell
Symptoms of autonomic dysfunction (eg, constipation,
sweating abnormalities, sexual dysfunction, seborrheic
dermatitis)
A general feeling of weakness, malaise, or lassitude
Depression or anhedonia
Slowness in thinking
Onset of motor signs include the following:
Typically asymmetric
The most common initial finding is a resting tremor in an
upper extremity
Over time, patients experience progressive bradykinesia,
rigidity, and gait difficulty
Axial posture becomes progressively flexed and strides
become shorter
Postural instability (balance impairment) is a late
phenomenon
Nonmotor symptoms
Nonmotor symptoms are common in early Parkinson
disease. Recognition of the combination of nonmotor and
motor symptoms can promote early diagnosis and thus
early intervention, which often results in a better quality of
life.


Diagnosis
Parkinson disease is a clinical diagnosis. No laboratory
biomarkers exist for the condition, and findings on routine
magnetic resonance imaging and computed tomography
scans are unremarkable.

Clinical diagnosis requires the presence of 2 of 3 cardinal
signs:
Resting tremor
Rigidity
Bradykinesia

Management
The goal of medical management of Parkinson disease is to
provide control of signs and symptoms for as long as
possible while minimizing adverse effects.

Symptomatic drug therapy
Usually provides good control of motor signs of
Parkinson disease for 4-6 years
Levodopa/carbidopa: The gold standard of symptomatic treatment

Monoamine oxidase (MAO)–B inhibitors: Can be
considered for initial treatment of early disease
Other dopamine agonists (eg, ropinirole, pramipexole):
Monotherapy in early disease and adjunctive therapy in
moderate to advanced disease
Anticholinergic agents (eg, trihexyphenidyl, benztropine):
Second-line drugs for tremor onlyonly

Treatment for nonmotor symptoms
Sildenafil citrate (Viagra): For erectile dysfunction
Polyethylene glycol: For constipation
Modafinil: For excessive daytime somnolence
Methylphenidate: For fatigue (potential for abuse and
addiction)
Deep brain stimulation
Surgical procedure of choice for Parkinson disease
Does not involve destruction of brain tissue
Reversible
Can be adjusted as the disease progresses or adverse
events occur
Bilateral procedures can be performed without a
significant increase in adverse events