Diagnostic Tests

  • For confirmatory test and tests for differential diagnosis of neurological diseases and syndromes, please see the page for the individual condition or use our seach our disease list.
  • Here is a brief description of the principles of neurological testing a links to the sections on the common neurological tests.

General principles of diagnostic tests:

There are several diagnostic tests that aid us in making the diagnosis in neurological disease. These tests do not replace clinical judgement and usually require clinical correlation. The most efficient method is applying the investigations as necessary to confirm or refute the top conditions in the differential diagnosis. The short list of conditions can be arrived at by following the neurological method of clinical assessment using the sequential questions;  what is the presentation or problem? where is the lesion? and then what caused the lesion? Here are some points to consider when planning your investigations.

  • What is the most likely diagnosis within the differential diagnosis?
  • What condition in the differential diagnosis is serious and important not to miss?
  • What condition in the differential diagnosis is treatable and important not to miss?

Remember that we treat individual patients and also treat patient populations. So both perspectives are necessary to contemplate:

  • Individual perspective: The individual patient ideally wants a comfortable, low cost and timely investigation plan that arrives at the correct diagnosis, and does not miss any serious or treatable diagnosis.
  • Population (community) perspective: Similarly we would like comfortable, low-cost, timely investigation plans that arrive at the correct diagnosis and avoids missing serious or treatable conditions. The additional perspective, is that you have to think of your ‘default’ protocol or system for approaching certain problems or conditions. Think about how you approach encephalopathy for example. What tests do you order in all cases? What tests are reserved for ony certain cases? What are the triggers/indications (the investigation threshold) for ordering those tests? How is your default plan/approach for encephalopathy arranged to be comfortable, timely, low-cost, effecient but  still effeciently arrives as the correct diagnosis without missing serious or treatable ones. This way you can have a system where the goals are met without ordering every concievable test for every patient.

The Neurological Investigations:

The investigations for each individual disease is covered under the page devoted to that disease. The investigations as they apply to each neurological presentation (problem) are presented under the respective sections. Here we provide an overview and further general information about the various neurological investigations and their interpretation.


Electroencephalography (EEG)
Nerve Conduction Studies and Electromyography (NCS/EMG)
Evoked potentials:

  • Motor evoked potentials MEP
  • Somatosensory evoked potentials SSEPs
  • Brainstem auditory evoked response BAER

Autonomic nervous system testing

Neuroimaging and Neuroradiology (CT, MRI, PET, SPECT, TCD, CUS etc)

Neuroimaging is an integral part of practicing and learning neurology; not to mention neurological research. Here are some notes to get you started.
Approach to CT head
Approach to MRI brain
Approach to MRI spine
Approach to CTA head and neck (…coming soon)
Approach to MRA head and neck (…coming soon)
Carotid Ultrasound
Transcranial Doppler Ultrasound (TCD)