Parkinson’s Disease: Diagnosis and Treatment

Diagnosis

Diagnosis of Parkinson’s disease is generally made by the characteristic clinical presentation, including history, physical examination, and neurologic examination.

Although there are no commonly available confirmatory tests or imaging modalities, clinical response to a dopamine agonist strongly suggests the diagnosis.

A CT scan, MRI, and/or laboratory testing may be indicated in equivocal cases to rule out other diagnoses (Wilson’s disease, Huntington’s disease, cerebrovascular disease, normal pressure hydrocephalus, mass lesions). However, imaging is generally only indicated if the presentation is atypical or if focal symptoms are present.

Treatment

Parkinson’s disease follows a progressive course. The disease advances in all cases, but the rate of progression varies, with younger patients typically progressing more rapidly. While there is no definitive cure available, medical treatment can alleviate many of the symptoms.
           
Adjuvant Therapies

Physical, occupational, and speech therapies are often beneficial, and social work consultation can help make daily living at home easier for the patient and prevent further disability.

Medications

Medications that might cause parkinsonian symptoms should be discontinued and alternative drugs used if necessary. Treatment is primarily aimed at increasing the availability of dopamine to the CNS.

Levodopa (a dopamine metabolic precursor) plus carbidoba (which  antagonizes the catechol–O–methyltransferase enzyme that would otherwise inactivate levodopa prior to reaching the brain) have proven to be the most effective therapy to improve symptoms. However, the drugs do not seem to affect the disease’s progression. 

Catecholamine–O–methyl–transferase (COMT) inhibitors (entacapone, tolcapone) may slow the breakdown of dopamine, which is often helpful if the effect of levodopa is too short. It is prudent to be aware of potential liver toxicity with use of tolcapone.

Dopamine agonists may improve symptoms (bromocriptine, pergolide, pramipexole, ropinerole). Pergolide can contribute to fibrosis.

Selegiline impedes the breakdown of dopamine and may also prolong the action of levodopa.

Amantidine may be useful for its mild anti–parkinson’s effects, but also as a mild psychostimulant and a treatment for dyskinesias.

Symptomatic treatment may be useful for hallucinations (clozapine, quietiapine), severe dyskinesias (amantadine), and tremor (benztropine).

Surgery

Surgical approaches (thalamotomy, pallidotomy, subthalamic deep brain stimulation) may have a role in advanced disease, especially in patients with severe intractable dyskinesia, tremor, or rigidity.