Striatonigral Degeneration Workup

Updated: Nov 13, 2019
  • Author: Ahmad El Kouzi, MD; Chief Editor: Selim R Benbadis, MD  more...
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Workup

Approach Considerations

No laboratory studies are diagnostic for multiple system atrophy with predominantly parkinsonian features (MSA-P). If a family history is noted, then testing for the SCA-3 mutation can identify Machado-Joseph disease.

Electromyography

Electromyography shows denervation of the external sphincter (urethral or anal); however, normal findings do not exclude the disease.

Clonidine growth hormone test

Studies show that after infusion of clonidine, serum growth hormone concentration does not subsequently rise in patients with multiple system atrophy. In contrast, the normal response, an increase in secretion, is found in Parkinson disease, pure autonomic failure, and control subjects. [18, 19]

Neuropsychiatric evaluation

Studies suggest that cognitive impairment is more common than previously thought in multiple system atrophy. Due to the nature of the deficits associated with this disease, the standard mental status examination has been found to be a poor tool for assessment. Neuropsychiatric testing is more sensitive and may be more a more helpful resource in multiple system atrophy. [16]

Sleep studies

Sleep disorders, particularly nocturnal stridor and REM sleep behavior disorder, are common in multiple system atrophy. Formal sleep studies should be considered, as research suggests that treatment can improve survival and quality of life. [20]

REM sleep behavior disorder is common in Parkinson disease and atypical parkinsonian disorders including striatonigral degeneration (MSA-P). Clonazepam is an effective treatment for many patients. Nocturnal stridor is specific to MSA and is produced by vocal cord dysfunction during sleep. CPAP is appropriate for long term treatment. [21]

Histologic findings

Findings in MSA-P include widespread glial cytoplasmic inclusions (primarily in oligodendrocytes) and, to a lesser degree, neuronal cytoplasmic inclusions and neuronal nuclear inclusions. Immunostaining of inclusion bodies reveals the presence of alpha-synuclein fibrils. [22]

Other tests

Autonomic tests for orthostatic vital signs such as the tilt-table test and urodynamic studies can be conducted. Scintigraphy with iodine-123-metaiodobenzylguanidine (MIBG) has recently shown utility in the differential diagnosis between Parkinson disease and multiple system atrophy; this method shows high sensitivity and adequate specificity in this field. [23]

A study measuring the clinical utility of skin biopsy for differentiating between Parkinson disease and multiple system atrophy concluded that detection of alpha-synuclein aggregates on cutaneous nerves in distal body sites is insufficiently sensitive; however, intraepidermal nerve fiber density (IEND) may be useful for this purpose. Further study is needed. [24]

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Imaging Studies

Computed tomography (CT) scans may show cerebellar or brainstem atrophy late in the course of the disease.

A study using single-photon emission CT (SPECT) scanning revealed significantly decreased cerebellar and dorsolateral prefrontal perfusion in patients with multiple system atrophy, relative to that of control subjects. [16]

Magnetic resonance imaging (MRI) may show 1 or more of the following [25] :

  • Atrophy of the putamen is best seen on inversion-recovery coronal sequences and/or putaminal hypointense signal on T2-weighted sequences. In rare instances, hyperintense bands lateral to the putamen may be seen.

  • There may be narrowing and hypointensity of the pars compacta of the substantia nigra, which can give the appearance of fusion between the pars reticularis and the red nucleus.

  • In a retrospective review, identification of the pontine "hot-cross bun" sign on T-2 weighted MRI sequences supported the diagnosis of MSA. [26]

Positron emission tomography (PET) scans demonstrate decreased postsynaptic D2-receptor density and impaired uptake of fluoro-L-dopa. [27] The recently approved DaTscan single-photon emission computed tomography (SPECT) imaging can help confirm the diagnosis of parkinsonism but does not distinguish idiopathic Parkinson disease from multiple system atrophy. [28]

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