Multiple system atrophy (MSA) is a progressive degenerative neurological disorder clinically defined as a combination of motor (parkinsonian MSA [MSA-P] and/or cerebellar MSA [MSA-C]) and autonomic (orthostatic and/or bladder) disorders by the second consensus statement on the diagnosis of MSA. In contrast, recent prospective cohort studies have shown that up to 18.2% of MSA patients start with bladder dysfunction alone that might last up to 7 years, suggesting that the disease process of alpha-synuclein aggregation might begin in the sacral spinal cord. However, a question arises as to whether we are able to diagnose very early, ‘pre-motor’ MSA.

A case report.

A 52-year-old, previously healthy Japanese man with no family history gradually developed difficult urination (poor stream, intermittent voiding, sensation of post-void residual (PVR)) and daytime urinary frequency 4 years prior. A local urologist was taking care of him, and this patient showed an Overactive Bladder Symptom Score of 1/15 and an International Prostate Symptom Score of 10/35, indicating difficult urination. His PVR volume varied from 74 ml to more than 500 ml. Ultrasound echography showed a quasi-normal prostate volume of 23 ml (normal < 20 ml) without protrusion of the inner gland, and his prostate-specific antigen was normal. However, cystoscopy revealed marked trabeculation, suggestive of neurogenic etiology. He had no history of motor disorder. 
Urodynamics-sphincter electromyography revealed detrusor hyperactivity with impaired contraction and neurogenic changes of the sphincter motor unit potentials. He did not have detrusor-sphincter dyssynergia. While he had no cerebellar ataxia or parkinsonism, he was revealed to have silent cerebellar hypoperfusion by brain SPECT scan, and slight cerebellar atrophy by brain MRI scan. Although he lacked a motor disorder, all these features suggested probable multiple system atrophy-cerebellar form (MSA-C). We started him on clean, intermittent self-catheterization. His urological, neurological, and neuroimaging findings did not change for two years thereafter, except that his voided volume gradually decreased to 0-50 ml (complete retention), and he spoke in a slightly unclear voice. We are following him carefully.

Up to 18.2% of MSA patients might have bladder dysfunction alone up to a 7 year-period from the onset. However, it seems to be difficult to diagnose this very early, i.e., during ‘pre-motor’ MSA in situ. As far as we know, this is the first such case. Our case raises two clinical issues. The first issue is that ‘pre-motor’ MSA patients who should not have urological surgery at a urology clinic visit urologists first. There are three urologic features in MSA. The first is a large PVR > 100 ml (by ultrasound) without marked prostatic hyperplasia in men. Urodynamics in such MSA patients often reveal DHIC. The third feature is sphincter EMG abnormality, i.e., neurogenic motor unit potentials. 
The second issue is that ‘pre-motor’ MSA patients will be referred from urologists to neurologists when seeking a final diagnosis. Initially, neurologists will exclude common neurologic conditions that might present with urinary retention due to lumbar spondylosis, diabetic neuropathy, spinal bifida occulta in young adults. etc. No report has thus far explored the diagnosis of MSA in situ in sacral autonomic disorder. In contrast, neuroimaging studies have shown that FDG-PET and MRI are able to detect cerebellar hypometabolism and atrophy in asymptomatic patients with familial cerebellar ataxia in situ.1 Also, brain DAT scans are able to detect striatal denervation in MSA-C patients with no clinical parkinsonism in situ.2 Therefore, according to these reports, a combination of neuroimaging modalities might be the best choice for diagnosing ‘pre-motor’ MSA in situ.

The present case report suggests that neuroimaging helps in the diagnosis of ‘pre-motor’ MSA-C in situ.

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