The neurological physical assessment of persons with acquired brain injury related neurological impairment can be complex and fraught with challenges regarding both form and interpretation. These challenges are more significant the less specifically trained the clinician is in neurological assessment and validity assessment more specifically. It is also made more challenging when basic neurologic exam findings are expected to be normal as it is the case with patient’s following concussion. Validity assessment, although not adequately thought and training were discussed in clinical practice, is a critical piece of any holistic assessment of any individual claiming impairment or functional disability following an acquired brain injury for several important clinical, legal and ethical reasons.
One key issue that is often inadequately taught during professional training is that of validity assessment in the context of the neurological exam. As neurorehabilitation professionals, it is important to understand the nuances involved in thorough neurological physical examination of patients following any type of acquired brain injury. There is a clear need for understanding specific validity assessment techniques the can be utilized in this context and to understand how these findings should be integrated with the rest of the neurological exam. It is just as important that clinicians learn how to interpret abnormal findings as they reveal themselves and understand if, in the context of the condition being examined, such findings make sense relative to the spectrum of neurological impairment that could be associated with that specific condition.
This identifying a person is having significant cognitive impairment can lead to inappropriate interventions including unnecessary drug prescriptions, therapies, academic or work accommodations among other incorrect prescriptions that only perpetuate perceptions of illness and probable gait work disability. Conversely, underestimating function due to poor effort or invalid test performance may obscure other causes of symptoms such as ones generated by psychoemotional problems such as depression, anxiety PTSD or other conditions such as chronic pain. Particularly after concussion, subjective complaints often do not match objective neurological findings. Some individuals may exaggerate (either consciously or unconsciously) their symptoms and potentially signs on physical examination for a variety of different reasons.
Clinicians must remember that “abnormal” neurologic physical exam findings may be organic, non-organic or a combination of both. It must also be remembered that psychogenic or so-called functional disorders can coexist with organic neurologic disorders in up to 60 percent of patients. As an example of the prevalence of non-organic presentations, symptoms considered functional or medically unexplained account for about one third of all new referrals to neurology outpatient departments/clinics.
Validity assessment, in general, and as specific to the neurological physical exam is paramount in both clinical and clinicolegal contexts as without such assessment practitioners cannot develop medically probable opinions based upon an objective foundation nor come to accurate conclusions about the actual degree of impairment resulting from neurological injury or disease. As clinicians, we are taught to believe our patients (not just what they say but how they present on exam). This practice and inherent training bias tends to color our approach to assessment and may narrow the scope of differential diagnostic considerations, particularly when evaluating more complex cases.
As clinicians, we must understand that patients and clinicians alike have biases that may enter into the mix of sign and symptom reporting, neurological physical examination findings, as well as clinician interpretation of same. Good clinical or clinicolegal assessment requires an eye to detail and inclusion of reasonable measures to assure the validity of reported signs, as well as symptoms. A critical piece of the art of validity assessment is to assure that optimal effort is encouraged by the examiner and being exerted by the patient or examinee in the context of the specific neurological physical exam assessments conducted.
It is important to acknowledge the differences between performance and symptom validity in the context of the aforementioned discussion. Performance validity refers to validity of actual test performance, whether neuropsychological or otherwise; whereas, symptom validity refers to the validity of the patient/examining symptom report (whether in regard to cognitive, behavioral or somatic complaints). Clinicians need to become familiar with how to gauge both types of validity.
Various factors can produce invalid neurological exam physical findings and/or interpretations including patient/examinee, as well as clinician/examiner biases, as well as, sub-optimal patient/examinee effort and engagement. Taking a careful and detailed history is important in the context of validity assessment. Historical facts such as a prior history of functional complaints, multiple lawsuits and injuries, models for illness, affective illness, external incentives, primary gain incentives, ongoing litigation, recent stressors, illness beliefs (including those culturally based) and childhood/prior traumatic life experiences (i.e. physical, emotional or sexual abuse) must all be taken into consideration. In the context of interpretation of findings, examining practitioners should understand the neurology and neuropathology of the neurological disease process being evaluated (if known) and the neuropathology, if any, in those conditions that may not have a diagnostic label.
Functional neurological physical exam abnormalities may be pseudo-neurological in origin secondary to disorders such as conversion disorder (now termed functional neurological symptom disorder [FNSD], exaggerated (implying that some level of impairment is present but is being amplified), suppressed, or feigned, the latter either in the context of malingering or factitious disorder. Clinicians should also be familiar with some of the more common FNSDs including pseudoparalysis, pseudosenosry syndromes, non-epileptic psychogenic seizures, pseudocoma, functional gait disorders, pseudo-neuroophthalmologic syndromes and functional aphonia.
As with any part of a good examination, clinician should rely on objective evidence before opining either in the clinical context or medical legal 1 about what exactly is going on with a particular patient as far as the underlying symptom & generators. As part of validity assessment it is also critical to understand whether a particular patient/examinee is putting forth adequate/optimal effort in the context of completing any assessment that they must undergo as part of their evaluation. In that context, there are now multiple measures that provide information to the clinician in this regard. Another area of importance to consider is that of response bias tendencies on the part of the patient/examinee. More specifically, the ideal patient is 1 who neither has a negative or positive response bias but answers questions “write down the middle”. Assessment of response bias should also be integrated into the overall validity assessment of any patient.
If the reader is interested in additional information on this topic then the following are recommended:
- Lees-Haley, PR, Williams, CW, Zasler, ND, Margulies, S, English LT & Steven KB: Response bias in plaintiff’s histories. Brain Injury. 11(11):791-799, 1997.
- Martelli, M.F., Zasler, N.D., Pickett, T.C.: Integrated neuropsychologic and neuromedical assessment of response bias following ABI. Archives of Clinical Neuropsychology. 15:661, 2000.
- Martelli, M.F., Zasler, N.D., Bush, S.S.: Assessment of response bias in impairment and disability examinations. In: L. Carrion & G. Zitnay (Eds): “Practices in Brain Injury”. 2007.
- Martelli, M.F., Nicholson, K, Zasler, N.D.: Assessing of response bias. In: Brain Injury Medicine: Principles and Practice. Second edition. Zasler, D. Katz, R. Zafonte (Eds.). New York. Demos Publishers. 1415-1436, 2013.
- Zasler, N.D., Martelli, M.F.: Response bias assessment in claimed cognitive impairment following ABI. Journal of Legal Nurse Consulting. 13(4)7-14, 2002.
- Zasler ND: Validity assessment and the neurological physical exam. 36(4):401-13, 2015.
- Zasler, N.D., Bigler, E. Medicolegal issues in traumatic brain injury. In: Traumatic Brain Injury. Physical Medicine Rehabilitation Clinics of North America. Editors: C. Eapen and D.X. Cifu. Elsevier. Philadelphia. 28(2):379-391, 2017.
- Zasler N, Bender S. Validity assessment in traumatic brain injury impairment and disability evaluations. Medical Impairment and Disability Evaluation and Associated Medicolegal Issues. Physical Medicine and Rehabilitation Clinics. 30(3): 621–636, 2019.
- Zasler ND, Bender S. Validity assessment in traumatic brain injury impairment and disability evaluations. In: Medicolegal impairment and disability evaluation and associated medical legal issues. PM&R Clinics of North America. Editor: R. Rondinelli and M. Eskay-Auerbach. Philadelphia, PA. 621-636, 2019.
- Zasler ND, Ameis A, Martelli MF, Bush S. Clinicolegal issues. Zasler ND, Katz D, Zafonte R (eds): Brain Injury Medicine: Principles and Practice. Third Edition. Demos Publishers. New York, NY. 1293 – 1317, 2022.
