Tools Used for Neurological Examination in Stroke
Early detection of stroke is essential in order to improve outcomes and decrease long term disability. Clinicians in both out of hospital settings and in hospital settings use various tools to determine the likelihood of stroke in patients with symptoms suggestive of stroke.
Quick recognition in the prehospital setting allows the receiving facility to mobilize the stroke team as the patient is en route to the facility. Notifying the emergency department that the patient is likely suffering a stroke can lead to quicker imaging, which in turn means faster delivery of fibrinolytic therapy or PCI (percutaneous coronary intervention).
Acute stroke treatment is time dependent, and the faster a stroke can be identified, the better the outcome for most patients. Although it may seem that a matter of minutes cannot possibly make much of a difference, when it comes to stroke it can and it does, hence the saying “Time is Brain”. As a response to the need for standardized stroke assessment, various stroke screening tools or scales have been developed. Although the scales do not predict the outcome after a stroke, they can be very useful as a triage tool. A standardized scale also helps prevent variations among emergency service personnel and first responders who are evaluating a patient for stroke.
Scales in Use
There are a few different scales that are commonly used in the assessment of stroke, including those listed below:
The Cincinnati Prehospital Stroke Scale: This scale tests for three possible signs of stroke, including facial droop, arm drift and speech abnormality. One abnormal finding out of three means that there is a greater than 70% chance that the patient is experiencing a stroke, while three abnormal findings indicate a >85% probability of stroke.
An obvious advantage of using the Cincinnati Prehospital Stroke Scale is that it is fast. The evaluation can usually be completed in less than a minute. In some situations, using the fastest stroke scale may be most beneficial. One possible disadvantage to using this stroke scale is that it only based on a few parameters, therefore it may not be an efficient way to assess for a posterior circulation stroke, which may cause symptoms such as dizziness and vomiting and is responsible for 5 to 10% of all ischemic strokes.
The Los Angeles Prehospital Stroke Screen: This stroke scale measures facial droop, arm strength and hand grip. In addition to these parameters, it also takes into consideration the patient’s age, whether or not the patient has ever had a seizure and the length of time symptoms have been present. The screen also evaluates blood glucose level and whether at baseline the patient is bedridden or wheelchair bound.
The main drawback to using the Los Angeles Prehospital Stroke Screen is it may take slightly longer to complete than the more succinct Cincinnati Prehospital Stroke Scale.
The National Institutes of Health Stroke Scale (NIHSS): This stroke scale may be used to identify the likelihood of a stroke; it can also estimate severity. It measures 11 clinical functions or deficits such as gaze, vision, level of consciousness and facial palsy. It also measures limb ataxia, sensory loss, dysarthria and language. Arm and leg strength, along with inattention, are also evaluated. The items must be administered in order and without patient coaching.
Because the scale measures more parameters than the previously mentioned stroke scales, it may also help to rule out other causes of a patient’s symptoms. Although it may be completed in six to ten minutes, the assessment is far longer than some other stroke scales.
One benefit of using a stroke scale is that it provides a standardized tool for initial neurological evaluation. The type of scale selected may vary depending on employer or facility policy. For example, certain emergency service agencies may utilize a specific stroke scale. If personnel have the option to use different stroke scales, they should choose a scale that appears to be appropriate for the situation and the patient’s condition. They should also use a scale that they are very familiar with.
It is difficult to say which scale is superior to another. Different situations may call for the use of different scales. For example, if a rapid assessment needs to be performed, the Cincinnati Prehospital Stroke Scale may be the most advantageous. In other situations, a more thorough assessment may be warranted. It is also important to keep in mind that, although a stroke scale is a useful tool, it is only one piece of the puzzle.
Juach, E. Cucchiara, B. 2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care. Circulation. 2010. http://circ.ahajournals.org/content/122/18_suppl_3/S818.full Accessed August 2014.
Kidwell, CS, Startman, S. Identifying Stroke in the Field; Prospective Validation of the Los Angeles Prehospital Stroke Screen. http://www.ncbi.nlm.nih.gov/pubmed/10625718 August 2014.