Causal Pathway: Diagnosis of Parkinson's Disease Legends

¹Principal Symptoms Present:

*Two or more present, one of which is resting tremor or bradykinesia

1. Rigidity affecting one or more limbs, cogwheel in nature
2. Resting, postural tremor most often asymmetrical, 3–7 Hz, hands preferentially affected
3. Bradykinesia (akinesia, hypokinesia)
4. Postural/Gait disturbance often appears late in disease

²Principal Symptoms May Be Present:

*One or more may be present

1. Rigidity affecting one or more limbs, may or may not be cogwheel in nature
2. Tremor may be asymmetrical, but frequently bilateral and higher frequency (5–12 Hz). Head, voice, tongue, palate, leg and/or trunk tremor may occur
3. Bradykinesia
4. Postural/Gait disturbance

³Secondary Symptoms May Be Present:

1. Psychiatric symptoms (depression, anxiety, psyshosis)
2. Autonomic dysfunction (sexual dysfunction, orthostatic hypotension)
3. Gastrointestinal dysfunction (constipation, weight loss, dysphagia)
4. Urologic dysfunction
5. Speech and swallowing problems
6. Falls
7. Sleep disturbances
8. Visual disturbances
9. Cognitive dysfunction (dementia)
10. Olfactory dysfunction
11. Difficulty writing

⁴Secondary Symptoms May Be Present:

(as above)

⁵Radiology/Laboratory Tests not as useful in diagnosis:

Results of computed tomography (CT), magnetic resonance imaging (MRI), cerebrospinal fluid analysis, and electroencephalography (EEG) are usually normal and of little diagnostic asistance.

Positron-emission tomography (PET scan) using radio-labeled dopa may be helpful in confirming a diagnosis.

⁶Radiology/Laboratory Tests helpful in diagnosis of other conditions:

CT, MRI useful to eliminating other disease processes such as tumors, strokes, hydrocephalus, etc. Laboratory investigation should be performed when atypical symptoms exist, there is a strong family history or early age of onset.

Causal Pathway: Treatment of Parkinson's Disease Legends

For all medications, start with low dose, increase dose slowly until:

symptoms abate OR

maximum dose is reached OR

intolerable side effects occur.

Only make one medication change at a time.

¹ MAO-B Inhibitors: Monoamine oxidase B inhibitors (for neuroprotection):

² Seligiline, Rasagiline

³ Dopamine Agonists : Bromocriptine, Pergolide, Pramipexole, Andropinrole,

⁴ Cabergoline, Ropinirole, Apomorphine (activate dopamine receptors)

⁵ Other Modalities: Rehabilitation, Physical Therapy, Occupational Therapy, Speech Therapy, Counseling, Dietary Changes.

⁶ L-DOPA/PDI: Levodopa/Carbidopa (peripheral decarboxylase inhibitor)

⁷ Disabling tremor: may occur any time during the course of the disease.

⁸ COMT inhibitors: Catechol-O-methylransferase inhibitor: Tolcapone, Entacapone

⁹ Anticholinergic agents: Trihexylphenidyl, Benztropine, Procyclidine

¹⁰ Surgical interventions: pallidotomy, thalamotomy, deep brain stimulation, fetal nigral implants.

¹¹ Atypical Neuroleptic agents: Clozapine, Olanzapine, Quietipine

Many aspects of this causal pathway are controversial, including when to initiate therapy with L-DOPA, and when to use other agents. Monitoring for toxicities should be done throughout treatment, and is not specifically mentioned in this pathway. Similarly, physical therapy, counseling, speech therapy, and rehabilitation should start as soon as PD is diagnosed, and continue indefinitely.

The causal pathways are not clinical practice guidelines, nor are they algorithms for decisions in patient care. They have been constructed solely for use as guides during this systematic review of the literature.