An Older Man with Ambulation Difficulties

A 70-year-old man presents complaining of “not being able to move.” He cannot precisely remember time of onset, but it is certainly subacute, dating back several months. Recently, he has been unable to rise from several of his soft chairs and sofas where he typically likes to sit. His wife also has noted a fine tremor at rest in his left hand and fingers. His mentation is maintained and excellent; he has had no speech disturbances or gross weakness. However, he notes difficulty and slowness in initiating walking, which eases once he “gets going.”

History

He has type 2 diabetes that is well-controlled with metformin and diet. He also has hypertension for the past 10 years, which is treated with an angiotensin-converting enzyme (ACE) inhibitor and intermittent use of a diuretic.

Physical Examination

Physical exam reveals normal vital signs and cardiovascular findings. His gait reveals slowing with a loss of arm swing on the left more so than right. Testing confirms difficulty rising from a deep chair. There is a resting tremor of the left hand and fingers, which resolves when he purposely uses the hand. There is rigidity on the left hand and arm, but strength and reflexes appear normal both in the effected limb and elsewhere.

Which of the following is the most likely diagnosis?

A. Diabetic neuropathy

B. Guillain-Barré syndrome

C. Parkinson’s disease

D. Myasthenia gravis

(Answer and discussion on next page)

Correct Answer: C

This patient presents with manifestations, including an asymmetric tremor at rest, rigidity, and bradykinesia—typical features of Parkinson’s disease (Answer C). Parkinson’s is an extremely common neurological disorder affecting perhaps 1% of people 60 years or older.¹ Its incidence increases with age but is uncommon below the age of 40.¹ Its pathophysiology involves disruption and degeneration of the dopaminergic neurons in the basal ganglia. Typical pathology reveals reduction in the number of such neurons and a typical inclusion body (ie, Lewy bodies) in those remaining. The core cause of Parkinson’s remains unknown.

Symptoms

More than anything else, Parkinson’s is a disorder of movement and decreasing ability to move—bradykinesia and rigidity. This set of symptoms is elicited in more than 75% of cases and includes a clumsy or weak limb, a stiff or uncomfortable “achy” limb, and a gait disorder characterized by a slow, shuffling (small steps) walk with loss of arm swing.¹ Despite the bradykinesia, there is retention of strength and reflexes to a significant degree on examination. 

The other signature finding in early Parkinson’s is a tremor. The tremor is a resting tremor, which actually disappears with voluntary movement and most commonly affects one hand. Like the other motor findings including bradykinesia, the tremor is asymmetrical in nature.¹ 

Diagnosis

The diagnosis can usually be made on clinical grounds. Diagnostic testing is usually performed to exclude other disorders, such as structural (eg, neoplastic, vascular) lesions of the brain. Attention needs to be paid to drug-induced Parkinsonism; a variety of frequently used drugs in older age populations (eg, phenothiazine and haldol) as well as antiemetics can cause a Parkinson’s syndrome that can be reversed when the drug is stopped. 

Finally, when atypical findings accompany Parkinsonism (eg, dementia, symmetry, Babinski signs, urinary retention), then other primary neurological diseases that have some associated Parkinson’s features need be explored. Note: Since there may be effective specific treatments and anti-Parkinson’s disease pharmacologic agents are usually not helpful.

Differential Diagnosis

Guillain-Barré syndrome (Answer B) and myasthenia gravis (Answer D) are 2 syndromes that also effect motor function, but both present quite differently from Parkinson’s. Guillain-Barré is an acute or subacute presentation; the main features of which are progressive, bilateral, relatively symmetric weakness in the limbs that plateaus within 12 hours to 28 days. There is hyporeflexia and areflexia. Our patient’s onset was chronic, over months, asymmetric, and without reflex changes.²

Myasthenia is an autoimmune disease, where autoantibodies target the neuromuscular junction of the axon/muscle cell membrane. Muscle weakness and fatigue occur during activity and improve with rest. Target areas are the eye and eyelids (eg, ptosis) and face with difficulty chewing, talking, and swallowing. None of these features were present in our case and, more typically for Parkinson’s, his gait actually improved as he walks more.

Diabetic neuropathy (Answer A) is always a diagnosis of exclusion. Although it can affect any nerve (sensory, motor, or autonomic), there is usually a significant sensory component with combinations of numbness, tingling, and burning in the feet and legs. The presentation is subacute, but unlike our case, the findings are usually symmetrical and there is no tremor associated with it.

Outcome of the Case

The diagnosis of Parkinson’s disease was made on clinical grounds. As the patient’s symptoms were significantly bothersome and interfering with quality of life, he opted for initiation of pharmacologic therapy in the forma of levodopa. After 3 months, his activities of daily living and abnormal motor features had significantly improved.

Ronald Rubin, MD, is a professor of medicine at Temple University School of Medicine and chief of clinical hematology in the department of medicine at Temple University Hospital, both in Philadelphia, PA.

References:

1.Yuki N, Hartung HP. Guillain-Barré syndrome. N Eng J Med. 2012;366:
2294-2304.

2.Nutt JG, Wooten GF. Diagnosis and initial management of Parkinson’s disease. N Eng J Med. 2005;353:1021-1027.