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Parkinson’s Disease

Study guide:

Definition: 
An idiopathic, slowly progressive, degenerative disorder.

  • Affects the basal ganglia, and characterized by TRAP (please check the clinical presentation section). 


Epidemiology:

  • It is the most common of all the akinetic–rigid syndromes.

  • Prevalence increases with age.

  • By the time of presentation, approximately 70% of the dopaminergic neurons in nigrotriatal pathways are already lost


​Risk factors:
No well known identified cause (idiopathic).

 

Pathophysiology:

  • Progressive degenration of the dopamenergic neurons in the Pars Compacta of the substantia nigra & locus correleus in the nigrostraiatal pathway ➔ Dopamine depletion.

  • The surviving neurons will have easinophilic hyaline intracytoplasmic inclusions➔Lewy Bodies➔ made up of aggregates of abnormally phosphyrlated α-Synuclein.

Clinical Presentation:​

Tremors

  • Resting tremors.

  • Pill-rolling feature.

  • Illegible handwriting.

Muscle Rigidity

  • Lead-pipe rigidity.

  • Cogwheeel rigidity on physical exam: combination of lead-pipe rigidity and tremors. 

Bradykinesia

  • Difficulty in initiating the movement and repeating it.

  • Impaired fine movements.

  •  Hypophonic dysarthia.

Postural and gait changes

  • Stooped posture and shuffling gait.

  • Late postural instability and ↑ risk of falls.

Facial Expressions

  • Mask-like face.

  • Blepharospasm. 

Other non-motor features 

  • Insomnia, and depression.

  • Seborrehic dermatitis, urinary and\or bowel incontinence.

  • Difficulty in swallowing.

  • Dementia in later stages. 

Diagnosis:

  • DX is mainly through clinical history and physical examination.

  • Others:

    • Dopamine transporter SPECT: through excluding other neurological disease.

      • In Parkinson’s Disease SPECT is normal.

If dementia appeared early in the disease think of Lewy body demntia.

Management:

  • Pharmacological:

    • First eliminate any other drugs that can cause parkinsonian side effects:

    • Neuroleptic drugs (chlorpromazine, haloperidol, perphenazine).

    • Metoclopramide.

    • Reserpin.

  • Surgical:

    • Deep brain stimulation: used when the patient is < 40 Y/O with severe symptoms or when the medications fail to establish a response.​

  • Prognosis:

    • Patients who have tremor as the major symptoms of Parkinson’s disease have better prognosis than those who have bradykinesia predominance.

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References:​

  • Le, Tao, Vikas Bhushan, and Herman Singh Bagga. First Aid For The USMLE Step 2 CK. New York: McGraw-Hill Medical, 2010. Print.

  • Sattar, Husain A. Fundamentals Of Pathology. Chicago: Pathoma.com, 2011. Print.

  • Yogarajah, Mahinda. Neurology. Edinburgh: Mosby/Elsevier, 2014. Print.

  • Agabegi, Steven S, Elizabeth D Agabegi, and Adam C Ring. Step-Up To Medicine. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins, 2013. Print.

  • Hauser, Stephen, and Scott Josephson. Harrison's Neurology In Clinical Medicine. 3rd ed. McGraw Hill. Print.

  • Kumar, Parveen J, and Michael L Clark. Kumar & Clark's Clinical Medicine. Print.

  • Merck Manuals Professional Edition,. 'Parkinson Disease - Neurologic Disorders'. N.p., 2015. Web. 24 Sept. 2015.

  • Goljan, Edward F. Rapid Review Pathology. Philadelphia, PA: Saunders/Elsevier, 2014. Print.

  • Rang, H. P, and M. Maureen Dale. Rang And Dale's Pharmacology. Edinburgh: Elsevier/Churchill Livingstone, 2012. Print.

  • Howland, Richard D et al. Pharmacology. Philadelphia: Lippincott Williams & Wilkins, 2006. Print.

  • Walker, Brian R et al. Davidson's Principles And Practice Of Medicine. Print.

  • Le, Tao et al. First Aid For The® USMLE. Print.

  • Missinglink.ucsf.edu,. 'Case 2 Microscopic Path'. N.p., 2015. Web. 24 Sept. 2015. (Figure-1). 

  • Medicine, Drexel, and Rapid-Fire Facts. 'Rapid-Fire Facts - United States Medical Licensing Examination Step 1 Dit With Dit At Drexel University College Of Medicine - Studyblue'. StudyBlue. N.p., 2015. Web. 24 Sept. 2015. (Figure 2).

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First author:         Roaa Amer
Second Authors:  Abdullah AlAsaad  

                            Lama AlLuhaidan

Reviewer:             Bayan Alzomaili
Format Editor :    Adel Yasky

                            Bayan Alzomaili 

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