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Avoiding false positive diagnoses of motor neuron disease: lessons from the Scottish Motor Neuron Disease Register
R J Davenport1, R J Swingler, A M Chancellor
1Dept of Clinical Neurosciences, University of Edinburgh, Western General Hospital, UK.
Objectives:
To describe the frequency and characteristics of those patients initially registered with the Scottish Motor Neuron Disease Register (SMNDR) but who subsequently had a diagnosis other than MND made (false positives), to analyse the features which led to a revised diagnosis, and to draw conclusions which might improve routine neurological practice.
Methods:
The Scottish Motor Neuron Disease Register is a community based, prospective disease register to identify and follow up all incident cases of motor neuron disease in Scotland. Fifty three patients out of a total of 552 registered are presented, who, after initial registration, were later excluded because they failed to satisfy the register's diagnostic criteria.
Results:
Seven of these patients were labelled as "MND plus" syndromes and may represent a distinct subset of MND. The remaining 46 patients had an alternative diagnosis made (false positive group), accounting for 8% of the total. In half of these cases, potentially beneficial therapies are available. The predominant reasons which lead to a diagnostic revision were: failure of symptom progression, development of atypical clinical features for MND, and investigation results.
Conclusions:
Patients with MND should undergo thorough and relevant investigations at presentation with the emphasis on neuroradiological imaging and neurophysiology; all patients should be followed up by an experienced neurologist, particularly those in whom symptoms and signs are restricted to either the bulbar or spinal muscles; failure of symptom progression or development of atypical features should lead to an early reassessment; finally, patients should be informed of the diagnosis only when it is secure.
Insights
Approximately 8% of patients initially registered for motor neuron disease (MND) were later diagnosed with other conditions. Key indicators for reassessment include lack of symptom progression and atypical features, ensuring accurate diagnosis and timely treatment.
Area of Science:
- Neurology
- Clinical Diagnostics
Background:
- The Scottish Motor Neuron Disease Register (SMNDR) prospectively identifies and follows all incident cases of motor neuron disease (MND) in Scotland.
- Understanding diagnostic discrepancies is crucial for refining clinical practice and patient care.
Purpose of the Study:
- To determine the frequency and characteristics of patients misdiagnosed with MND (false positives).
- To analyze factors leading to revised diagnoses.
- To provide recommendations for improving neurological practice in diagnosing MND.
Main Methods:
- Analysis of 53 patients out of 552 registered in the SMNDR who were later excluded due to not meeting diagnostic criteria.
- Review of clinical features, symptom progression, and investigation results for diagnostic revision.
Main Results:
- 8% of registered patients (46 out of 552) were false positives with alternative diagnoses.
- Seven patients were classified as "MND plus" syndromes.
- Common reasons for diagnostic revision included lack of symptom progression, atypical clinical features, and investigation findings.
- Potentially beneficial therapies were available for half of the false positive cases.
Conclusions:
- Thorough investigations, including neuroradiological imaging and neurophysiology, are essential at presentation.
- Regular follow-up by experienced neurologists is critical, especially for patients with restricted bulbar or spinal symptoms.
- Failure of symptom progression or atypical features warrant early reassessment.
- Diagnosis should only be confirmed when secure to avoid premature patient notification.