Hypotension and Incontinence in Late Parkinsonism

abstract & commentary

Source: Wenning GK, et al. Time course of symptomatic orthostatic hypotension and urinary incontinence in patients with postmortem confirmed parkinsonian syndromes: A clinicopathological study. J Neurol Neurosurg Psychiatry 1999; 67:620-623.

Neurologists and movement disorders physicians face a constant challenge to differentiate Parkinson’s disease (PD) from other neurodegenerative illnesses that cause parkinsonism. Grouped as "parkinson-plus" syndromes, this list includes multiple system atrophy (MSA), progressive supranuclear palsy (PSP), corticobasal ganglionic degeneration (CBGD), and diffuse Lewy body disease (DLBD). In this paper, Wenning and colleagues report on the use of two clinical complaints—orthostatic hypotension and urinary incontinence—in the differential diagnosis of parkinsonism.

Seventy-seven pathologically confirmed parkinsonian cases formed the basis for this study. Wenning et al examined the latency to onset, and duration from onset to death, of two autonomic complaints—symptomatic orthostatic hypotension and urinary incontinence. They found that the latency to onset of orthostatic hypotension was much longer in PD (166 months) than in any other cause of parkinsonism (30 months, on average). Similarly, latency to onset of urinary incontinence was longest in PD (144 months), of intermediate duration in PSP and CBGD, and of shortest duration in MSA (12 months). Assigning a one-year latency to symptom onset as a diagnostic cutoff, the positive predictive value of symptomatic orthostatic hypotension was 75% in MSA. In this series, no patients with PD, CBGD, or DLBD developed symptomatic orthostatic hypotension within the first year. The positive predictive value of urinary incontinence was 56% in MSA.

Commentary

This study, while important, is limited by several methodological flaws. There is unavoidable selection bias in any postmortem series, with a tendency to receive severely affected cases. Further, the data were collected retrospectively by reviewing clinical records, a notoriously unreliable proposition. Further, symptoms were not correlated with autonomic measurements, such as abnormal tilt-table testing or rectal EMG.

Despite these problems, this study offers several important lessons. First, latency to onset of two symptoms—symptomatic orthostatic hypotension and urinary incontinence—was helpful in distinguishing PD from other causes of parkinsonism. Second, the early appearance of orthostatic hypotension or urinary incontinence strongly suggested MSA, as opposed to other parkinsonian syndromes.

Does an accurate early diagnosis of MSA, PSP, CBGD, or DLBD help in the clinical management of these disorders? Since there is no therapy that affects the natural history of these disorders, and treatment is often only partially effective, one could argue that an accurate diagnosis is of limited importance except for academic interest. However, patients with MSA pose several challenges that warrant an attempt to secure an early diagnosis. First, as many as one-third of these patients respond to levodopa when given at adequate dose, often for many months. Second, identifying early autonomic dysfunction allows the clinician to protect patients from severe orthostasis by using Florinef and/or Midodrine. These agents allow levodopa to be administered at a dose adequate to achieve an antiparkinson effect, even in the presence of symptomatic orthostasis. Finally, patients with MSA are prone to vocal cord dysfunction, causing stridor and even occasionally nocturnal sudden death. Early recognition of these problems can lead to interventions that improve the quality and length of patients’ lives. —steven frucht, md

Latency to onset of which two symptoms was helpful in distinguishing Parkinson’s disease from other causes of parkinsonism?

a. Vocal cord dysfunction

b. Orthostatic hypotension

c. Urinary incontinence

d. b and c

e. a and b