Ask The Doctor

Dear Dr. Zasler,
Please share your thoughts on fatigue after brain injury.
Dr. Antonio Rodriguez

Dr. Rodriguez,
Thanks for your interesting question. Fatigue is a common, yet in my opinion, poorly understood phenomena following acquired brain injury and, in particular, traumatic brain injury. Fatigue complaints are quite common across the spectrum of injury severity, that is, from mild injuries involving concussion to the most severe injuries, even in the presence of relatively good neurologic recovery in the latter group.

Clearly, not everyone who sustains a brain injury complains of fatigue, yet it is certainly one of the "top 5" post-injury complaints.  Interestingly, there is not much literature on the exact cause of post-traumatic fatigue, never mind the appropriate differential diagnosis of subjective reports of fatigue and/or its’ treatments. 

As a clinician who has been involved with the management of persons with traumatic brain injury for some years, I would experientially share with the readership that it is my belief that a diagnosis of neurogenic fatigue is one of exclusion. 

Specifically, a diagnosis of neurogenic fatigue cannot be made clinically simply on the basis of a subjective report of fatigue by a patient or examinee when it is claimed to be temporally related to a history of acquired brain injury.  In fact, there are many causes of fatigue in general medical practice. 

As a matter of fact, if one looks at the general medical literature, the most common cause of fatigue is actually psychiatric, involving disorders of depression and anxiety.  These types of psychiatric diagnoses are not uncommon in persons with acquired brain injury and, therefore, they must always be considered as part of the differential diagnosis of fatigue complaints. 

Other common phenomena that may produce fatigue and/or contribute to it include sleep initiation and maintenance problems, sleep apnea, chronic pain of at least a moderate to severe intensity, medication side effects, late intracranial complications such as subdural hematomas or epidural hematomas, communicating hydrocephalus, shunt failure, occult infections, metabolic disorders such as hypernatremia (high sodium level) or diabetes insipidus (the latter resulting in low sodium levels), to name but a few.
I would also note that when patients with TBI are seen by physicians, there is often a propensity to apportion everything to the brain injury.  In fact, physicians must maintain a "blinders-off" approach to medical assessment and management.  Other conditions that may have nothing to do with the patient's injury, must be considered as etiologic factors in the differential diagnosis of fatigue.  These include such conditions as multiple sclerosis, hypothyroidism, anemia, pre-existing affective disorders, fibromyalgia, and chronic fatigue syndrome, among other conditions.

A thorough assessment requires time to take an adequate history to determine what issues may be problematic for the particular patient in question who presents with subjective complaints of fatigue.  It is also important to differentiate between cognitive and physical fatigue. 

Quite often, persons with acquired brain injury simply do not have the "cognitive reserve" to sustain mental effort.  They often report that they are initially able to do tasks without fatigue but with time and persistence at the task they become less cognitively efficient.  This type of fatigue is generally considered to be neurogenic and due to direct effects of the TBI. 

Physical fatigue on the other hand may or may not be a neurological consequence and we often find that persons following ABI are often quite physically deconditioned.  A regular aerobic exercise program can do wonders for fatigue complaints (not only in persons with brain injury!).  Such exercise not only results in a more conditioned individual but also, helps to improve general self image, sleep disorders and mood. 

Initial efforts to treat fatigue should involve addressing the “easy” issues (e.g. assuring proper sleep hygiene, appropriate management of pain, minimizing polypharmacy - in particular sedating medication(s), as well as, ruling out occult infection and/or endocrine disorders, among some of the other relatively simple interventions. 

I generally only recommend medication treatment for fatigue when there has been an adequate global assessment of the individual and such disorders as anxiety and depression have been either fully treated and/or ruled out.  Once the aforementioned has been done and if there continues to be functionally significant fatigue complaints, then I think it is appropriate to consider other interventions such as pharmacologic treatments. 

The historical mainstays of pharmacologic treatment have involved psychostimulants; however, naturopathic agents such as guarana, as well as, atypical agents such as modafinil can be considered. 

When appropriate, laboratory testing to exclude such conditions as anemia and hypothyroidism should be conducted based on the overall clinical presentation and exam.  With appropriate understanding of the various etiologies of fatigue, the clinician should be able to assist the patient with ABI in addressing this issue in a satisfactory manner.

Thanks again for your question.

Nathan D. Zasler, M.D., FAADEP, FAAPM&R, DAAPM
Medical Director, Concussion Care Centre of Virginia
Medical Director, Tree of Life
Chairperson, IBIA