Ultrasound excludes Parkinson’s disease in patients with sporadic symptoms

November 19, 2007

Transcranial brain sonography can exclude the diagnosis of Parkinson’s disease in patients experiencing sporadic symptoms. Using exams focused on the substantia nigra and lenticular nucleus, researchers found that the difference between idiopathic Parkinson’s disease and two other movement disorders is clearer in patients under 60 years old.

Transcranial brain sonography can exclude the diagnosis of Parkinson's disease in patients experiencing sporadic symptoms. Using exams focused on the substantia nigra and lenticular nucleus, researchers found that the difference between idiopathic Parkinson's disease and two other movement disorders is clearer in patients under 60 years old.

Dr. Uwe Walter and colleagues in the neurology department at the University of Rostock and the District Hospital Mainkofen in Deggendorf, Germany, published their study in the November issue of the Archives of Neurology.

An ultrasound technician, blinded to patients' clinical diagnosis, used transcranial ultrasound to study all patients admitted between 2003 and 2005 to the movement disorder clinic with Parkinson-like symptoms. Symptoms similar to those of idiopathic Parkinson's disease occur in two other movement disorders: probable parkinsonian variant of multiple system atrophy and probable progressive supranuclear palsy.

The patients studied included 82 men and 56 women with a mean age of 67.1 years, all with a clinical diagnosis of sporadic idiopathic Parkinson's disease. Disease duration was a mean of 7.5 years, and the mean score on the Unified Parkinson Disease Rating Scale was 32.6.

Ten women and 11 men with a mean age of 65.4 years also participated in the study. They had a clinical diagnosis of multiple system atrophy with probable parkinsonian variant and a 3.1-year mean duration of disease, rating a mean of 33.5 as a motor score.

Finally, 13 men and nine women with a mean age of 71.2 years and a clinical diagnosis of probable progressive supranuclear palsy were also included. Their mean duration of disease was 3.4 years, and their mean motor score was 46.2.

Of all these groups, only seven patients had insufficient temporal acoustic bone windows for transcranial ultrasound exams of their brains.

The researchers calculated the sensitivity, specificity, and positive predictive value of the ultrasound exams. They found that normal echogenic substantia nigra was a sign of parkinsonian variant multiple system atrophy, with a sensitivity of 90%, specificity of 98%, and positive predictive value of 86%. A combination of third ventricle dilation of more than 10 mm and hyperechogenic lenticular nucleus was a sign of progressive supranuclear palsy, with an 84% sensitivity, 98% specificity, and positive predictive value of 89%.

A normally echogenic substantia nigra combined with hyperechogenic lenticular nucleus indicated either progressive supranuclear palsy or parkinsonian variant multiple system atrophy, with a sensitivity of 59%, specificity of 100%, and positive predictive value of 100%.

In patients whose symptoms started when they were less than 60 years old, a normally echogenic substantia nigra alone was a strong indication of progressive supranuclear palsy or parkinsonian variant multiple system atrophy, excluding idiopathic Parkinson's disease, with a sensitivity of 75%, specificity of 100%, and positive predictive value of 100%.

The researchers concluded that transcranial ultrasound findings can clarify the diagnosis of patients with Parkinson-like symptoms, especially in patients whose symptoms started before age 60.