Postconcussion Syndrome: Diagnostic Characteristics and Clinical Manifestations

Erica Bellamkonda, Blessen C. Eapen, and Felise S. Zollman

GENERAL PRINCIPLES

Definition

Individuals sustaining a traumatic brain injury (TBI) often report a constellation of physical, cognitive, and emotional/behavioral symptoms. These symptoms typically resolve in days to weeks after the initial injury, but in some individuals these symptoms can persist beyond 3 months and may be referred to as postconcussion syndrome (PCS) [1,2].

[Note that throughout this text you will see the terms PCS and postconcussion disorder (PCD) used interchangeably.]

There is debate in the literature on a universally accepted definition of PCS; however, the International Classification of Diseases, 10^th Revision (ICD-10) provides broadly accepted research criteria for diagnosis of PCS [1].

ICD-10 CRITERIA

• A history of head trauma with loss of consciousness.

• At least one symptom from three of the following six groupings:

Headache, dizziness, general malaise, excessive fatigue, or noise intolerance

Irritability or emotional lability that is easily provoked; may be accompanied by depression and/or anxiety

Subjective complaints of difficulty with concentration, memory, or performing mental tasks without clear objective evidence of impairment

Insomnia

Reduced tolerance of alcohol, stress, or emotional excitement

Preoccupation with symptoms, fear of permanent brain damage, and/or adoption of sick role

DSM CRITERIA

The DSM-5 defines TBI as an injury resulting from impact to the head or other mechanism causing the brain to shift within the skull, with at least one of the following: loss of consciousness, posttraumatic amnesia, disorientation/confusion, or neurological signs such as evidence of injury on neuroimaging, seizures, loss of smell or hemiparesis.

Unlike its preceding edition, the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) does not contain the diagnosis PCD. In the DSM-5, persistent concussive symptoms are captured in the neurocognitive disorder (NCD) category, which contains disorders with acquired cognitive dysfunction as the core feature [3]. Unlike previous DSM editions, the DSM-5 offers criteria for diagnosing a TBI event and its severity, and considers the potential neurocognitive/neuropsychiatric sequelae attributed to it.

The DSM-5 diagnostic criteria for Mild and Major NCD due to TBI include evidence of cognitive decline from a previous level of performance not occurring exclusively in the context of a delirium and not better explained by another mental disorder (e.g., major depressive disorder, schizophrenia), with onset immediately following the occurrence of a TBI [3].

The essential distinction between Mild NCD due to TBI and Major NCD due to TBI is that, in the latter instance, cognitive deficits interfere with ability to perform every day activities such that assistance of another is needed.

In every circumstance, one must first ascertain that a precipitating TBI did in fact occur. If occurrence of a TBI cannot be asserted, then PCS and/or NCD due to TBI cannot be diagnosed.

EPIDEMIOLOGY

• The literature widely cites estimation that 1 year after injury, approximately 10% to 20% of persons will have persistent posttraumatic symptoms [4]. However, the accurate incidence and prevalence of PCS truly have not been established despite decades of research, largely because of limitations in subject recruitment (i.e., not all persons who suffer a mild TBI [MTBI] come to medical attention) in addition to over-diagnosis [5,6].

• The diagnosis of PCS is largely made based on subjective report of nonspecific symptoms, thus affecting prevalence [7].

• Individuals with positive early neuroimaging findings after MTBI have outcomes similar to those with moderate TBI [8], that is, protracted symptoms are more common in this subset of MTBI patients.

• Recurrent MTBI may be associated with long-term neurocognitive impairment [3].

PATHOPHYSIOLOGY

The initial symptom constellation reflects the neurometabolic cascade that occurs immediately following a TBI (described in Chapter 2). Symptom persistence has been attributed to both physiologic and psychological causes; however, it is mainly influenced by a variety of factors that ultimately affect how persons perceive their symptoms after MTBIs. Such confounding factors include personality traits, affective disorders, pain disorders, and medication side effects, among others [9] (see Figure 15.1).

Selected factors worth further mention include the following:

• Personality

Five personality traits are considered vulnerable to poor outcome: the overachieving, the dependent, the insecure, the grandiose, and those with borderline personality characteristics [10,11]. Alexithymia is characterized by difficulty identifying and describing feelings, externally oriented thinking, and limited imaginary thinking ability. Type D personality is characterized by negative affectivity and social inhibition [12].