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[WEB SITE] Neuropsychiatric Effects of Traumatic Brain Injury

From time to time every psychiatrist comes across patients whose problems are at least in part related to the neuropsychiatric consequences (behavioral, cognitive, and emotional) of traumatic brain injury (TBI). TBI affects approximately 2 of every 1000 persons per year. Those who are vulnerable to mental illness (eg, persons with alcohol abuse or antisocial personality disorder) are particularly at risk. Patients with TBI often have poor insight and may need hospitalization for their own safety. The neuropsychiatric and other sequelae are long-term; a head injury is for life.

A telling illustration from 1937 by Courville, a neuropathologist, nicely demonstrates why TBI is of interest to psychiatrists (see figure 1 in Fleminger 20091). The illustration is a composite of the location of contusions found in 50 patients who died of TBI.
The sites of specific vulnerability to contusions are the medial orbital frontal lobe and the anterior temporal lobes (Figure 1). Areas where contusions rarely occur include the primary motor, somato-sensory, and visual cortex. Therefore, areas of the brain concerned with social function and decision making are particularly vulnerable. It is unsurprising that neuropsychiatric sequelae outstrip neurophysical sequelae as the major cause of disability after TBI.

The neuropathology of TBI

Contusions are areas of cerebral bruising particularly involving gray matter, whereby blood leaks into the extravascular space. The contusion results in cell death and local loss of tissue. Diffuse axonal injury affects white matter anywhere throughout the cerebrum and brain stem. It may be followed by generalized atrophy with ventricular enlargement (Figure 2); this may take a few weeks or months to develop. Diffuse axonal injury in the brain stem is usually responsible for the slurred speech and severe ataxia that are seen in some severely disabled patients after TBI. Contusions and diffuse axonal injury may be complicated by anoxic brain injury that may occur soon after trauma because of poor cerebral perfusion secondary to raised intracranial pressure and focal strokes. In some patients, localized infarction occurs (Figure 3).

Neuropsychiatric assessment

The neuropsychiatric assessment starts by evaluating the severity of brain injury. In this way, the likely outcomes attributable to direct effects of brain injury can be determined, and any mismatch between these and what is observed can be attributed to psychological reactions or independent events. So, for example, in somebody with a severe psychotic illness that develops 3 months after an injury with no loss of consciousness, one can be fairly confident that the illness is not a direct consequence of the effects of brain injury on delusion formation. It is possible that the psychological trauma of the injury has allowed an acute psychotic reaction, or even that the injury was irrelevant and that the person was on the path to becoming schizophrenic anyway. On the other hand, it is likely that the psychotic illness is a direct effect of the brain injury in somebody in whom a delusional misidentification syndrome develops 3 months after an injury that was followed by coma for a week and delirium for several weeks.

The severity of brain injury is measured by the following:

  • Glasgow Coma Scale (used soon after injury)
  • Duration of loss of consciousness
  • Duration of posttraumatic amnesia (PTA), ie, the interval between the injury and the return of continuous day-to-day memories

The duration of PTA is particularly useful as a measure of the severity of the brain injury because it can be measured retrospectively, eg, in the clinic years after injury, and it is a good predictor of outcome.3 As a rule, if PTA lasts less than 1 week, a reasonably good outcome is expected. If PTA lasts longer than 1 month, significant disability is likely; a good proportion of those affected will not be able to return to work or to independent living. In general, younger individuals (those in their late teens or 20s) tend to do much better.

An MRI scan is essential in cases where the extent of damage is unclear because it may show unexpected brain injury. Gradient echo sequences are the most sensitive and should be undertaken, particularly in those with mild injury. A normal MRI scan does not rule out brain injury, but it does make significant disability as a direct effect of severe brain damage unlikely. Electroencephalography is usually not helpful, even as a predictor of posttraumatic epilepsy.

Neuropsychometric assessment can be useful in defining the severity of cognitive impairment and any areas of particular impairment. Such tests as the North American Adult Reading test are available and provide an estimate of the patient’s preinjury IQ. Such assessment is necessary for the accurate interpretation of a patient’s postinjury performance. Also, make sure that tests of executive function have been done. Note, though, that normal neuropsychometric test results do not rule out brain injury as the cause of problems with executive functions in everyday life.

Continue —> Neuropsychiatric Effects of Traumatic Brain Injury | Psychiatric Times

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