Multiple System Atrophy Differential Diagnosis

What is a Differential Diagnosis?

A differential diagnosis provides a sound way to evaluate the patient’s symptoms, list diseases likely to cause the symptoms, and eliminate those diseases less likely to be causing the patient’s clinical picture. Tests can help to confirm likely causes and rule out less likely diseases. Eliminating the less likely diseases helps clinicians more readily diagnose MSA.

Listed below are several conditions that should be eliminated through testing during a comprehensive differential diagnosis:

Parkinson’s Disease

Parkinson’s disease is a progressive neurodegenerative disorder that causes changes in motor and non-motor function. The key motor features are tremor, rigidity, reduced movement, and postural instability1. A resting tremor is a commonly recognized feature of PD. This often starts in one side of the body, in the hands or feet. Hand tremors can appear as if the individual is rocking the hand back and forth, often referred to as a “pill rolling tremor” in allusion to the pharmacists of old who would count pills. Resting tremors can also affect the lips, chin, jaw, and legs.

Rigidity is characterized with increased resistance with passive motion. Some describe the movement as “catching and release,” giving the sense of “cogwheel” rigidity.

Akinesia or bradykinesia is one of the most characteristic features of PD, as this involves difficulty in initiating movement tasks. This may present with speaking softly, decreased dexterity, reduced facial expression, and sleep disturbances. Over time, individuals might begin to feel slow in their movement, difficulty initiating and repeating actions, and stiffness of the limbs and body.

Postural instability typically presents later in the course of the disease and often causes walking disturbances known as freezing gait (feet getting stuck to the ground), a common cause of falls and hip fractures2. The timing of when postural instability starts is used as a clinical marker of differentiating PD from non-PD disorders, like MSA. The average time from the beginning of symptoms to the first fall is much longer in PD3. Among the non-motor signs, which commonly occur before the motor signs, is a decrease or absence of sense of smell. Other symptoms include forgetfulness and slowness in thinking. The diagnosis of Parkinson’s disease is made clinically.

Pure autonomic failure

Pure autonomic failure is a diagnosis of involving the peripheral autonomic nervous system (ANS). The ANS is responsible for controlling blood pressure, sweating, urinary habits, and impotence. Symptoms associated with pure autonomic failure include a drop in blood pressure (>20 mm Hg systolic) from lying down to sitting or sitting to standing, inability to sweat, and trouble maintaining an erection in men.

Progressive supranuclear palsy

Progressive supranuclear palsy (PSP) is a disorder similar to PD, where patients present with problems related to movement, falls, speech changes, difficulty swallowing, changes to vision, mood, and cognitive problems. It is estimated that 3-6 in 100,000 people worldwide, or approximately 20,000 Americans, have PSP. Some of the parts of the brain that are impacted by this disease include the frontal cortex and areas that control eye movements. One of the classic signs of PSP is the inability to direct eye movement downward, leading to blurry vision when attempted.

Dementia with Lewy Bodies

Dementia with Lewy bodies (DLB) is the third most common cause of dementia after Alzheimer’s disease and vascular dementia. This disease has symptomatic overlap with Parkinson’s disease, such as rigidity, balance, and posture instability. However, dementia with Lewy bodies typically presents with more prominent cognitive problems, hallucination, and fluctuations in cognitive function. Other symptoms of DLB include dysfunction of the autonomic nervous system, REM behavior sleep disorder, and memory changes.

Corticobasal Degeneration

Corticobasal degeneration initially presents with motor and/or cognitive difficulties. Individuals may have problems walking, more prominent limb rigidity, and inability to perform purposeful movements, and notice problems with speech. Some patients liken the limb problems to “my arm will not obey me.” Early on in the disease, the movement changes begin on one side such as the hands and legs, and later spread other limbs. Symptoms typically begin in the 60s.

Multiple Sclerosis

Multiple sclerosis (MS) is an immune-related disorder, where the body seems to mistake the brain for a pathogen. This disease predominately affects the spinal cord and brain. MS is more commonly found in women than men and geographically in Europe and North America. Some of the early symptoms present with a temporary loss of vision or motor movement. Diagnosis is made clinically, and with an MRI scan.

Spinocerebellar ataxia

Spinocerebellar ataxia is a genetic neurodegenerative disease that commonly presents in individuals 30-50 years old. The early symptoms seen are poor coordination of gait, speech, and arms. Diagnosis of spinocerebellar ataxia is predominately based on taking a thorough family history and neurological evaluation. Medical imaging and genetic testing may be used to support the diagnosis.

For all references listed in the About MSA section please download the MSA Coalition's "MSA - What You Need to Know"

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