Corticobasal degeneration

Parkinson's disease

Movement disorders

Progressive supranuclear palsy

Environmental health

Pediatrics

Parkinsonism

Psychology

Population

Medicine

Physical medicine and rehabilitation

Disease

Pathology

Movement Disorders Clinical Practice

We thank Dr. Daniel Richter and colleagues for their comments on our recently published Movement Disorders Clinical Practice (MDCP) article.1, 2 We welcome any guidance with regard to the diagnosis of atypical parkinsonism given that it can often be difficult especially at the first assessment. Often seeing the patient over time (“the tincture of time”) to identify “red flags” for atypical parkinsonism can help greatly. However, the resulting delay in diagnosis will prove a problem when disease-modifying treatments are available. The diagnosis is still a clinical diagnosis, and we await validation of various biomarkers to guide accurate diagnosis. Transcranial sonography (TCS) is one of these noninvasive biomarkers, and Richter and colleagues emphasise its role in distinguishing between idiopathic Parkinson's disease (IPD), MSA, PSP, and corticobasal syndrome (CBS). Several studies have used TCS to discriminate between atypical parkinsonian syndromes with limited success.3-6 The inclusion of hyperechogenicity in the SN and lenticular nucleus and third ventricular enlargement has increased the specificity (89% for PD; 99% for PSP; 95% for MSA; 91% for corticobasal degeneration [CBD]) of diagnosing atypical parkinsonism. However, TCS has a low sensitivity (67% for PD; 29% for PSP; 41% for MSA; 57% for CBD), with a high false-positive value of 35% in MSA and PSP patients. The positive predictive value is low for MSA and CBS (58% and 26%). The false positives SN echogenicity can occur in motor neuron disease, melanoma, and healthy population.7, 8 Thus, a positive result will be of help in distinguishing IPD versus MSA, but a negative result will be of limited use given that >50% of patients with MSA will have a normal TCS. We agree with Richter and colleagues that a large, prospective clinico-TCS-pathological study is needed to help define the potential role of TCS in the diagnosis of parkinsonism. Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique. V.P.: A D.A.O.: A S.B.: B A.C.: B M.O'C.: B M.F.: B T.L.: A The authors confirm that the approval of an institutional review board was not required for this work. Informed consent was obtained for this article. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines. The authors report no sources of funding and no conflicts of interest. S.B. received a travel grant from the Merck Serono limited, UK to attend a dystonia update meeting in London.

Reply to Comment on: A <scp>57‐Year‐Old</scp> Woman With Progressive Left Hand Clumsiness and Falls

Reply to Comment on: A 57‐Year‐Old Woman With Progressive Left Hand Clumsiness and Falls