Closed Head Injury Workup

Updated: May 04, 2022
  • Author: Leonardo Rangel-Castilla, MD; Chief Editor: Brian H Kopell, MD  more...
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Workup

Laboratory Studies

Lab studies include the following:

  • Serum levels of 2 biomarkers correlating with degree of brain injury, with GFAP more reliable up to 7 days after impact: glial fibrillary acid protein (GFAP), ubiquitin C-terminal hydrolase (UCH-L1) [1]

  • Complete blood count (CBC) including platelet count

  • Blood chemistries

  • Prothrombin time (PT) or international normalized ratio (INR)

  • Activated partial thromboplastin time (aPTT)

  • Anticonvulsant (eg, phenytoin) level: For patients who have been previously loaded or who were previously taking anticonvulsant medication, to ensure therapeutic levels

Serum sodium, urine specific gravity, urine osmolarity, and serum osmolarity tests should be ordered for individuals with urine output ≥250 mL/hr for 3 or more consecutive hours (pediatric patients, >3 mL/kg/hr) and for patients thought to have diabetes insipidus. Large doses of mannitol can mask diabetes insipidus by producing high urine output.

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Imaging Studies

Computed tomography (CT) of the head and magnetic resonance imaging (MRI) are used to measure changes in anatomic or physiologic parameters of TBI. These include hemorrhage, edema, vascular injury, and intracranial pressure. However, for most cases of mild TBI, CT and MRI often show no abnormalities. [1]

Diffusion tensor imaging (DTI) is used to detect axonal injury for patients with mild to moderate TBI. [1]

Functional MRI (fMRI) is often used to differentiate patients with TBI from control groups and has been used to study activation patterns in patients with TBI. [1]

Perfusion single photon emission computed tomography (SPECT) is used to measure cerebral blood flow and activity patterns. [1]

Computed tomography scanning of the head is the criterion standard for patients with acute closed head injuries. [53] A head CT scan is warranted, except for patients with only minor head trauma who are neurologically intact and are not intoxicated with drugs or alcohol. Advantages and disadvantages of head CT scan are summarized in the following table.

Table 3. Advantages and Disadvantages of CT Scanning in Head Trauma Evaluation (Open Table in a new window)

Advantages

Disadvantages

Noninvasive and rapid

Traumatic vascular lesions may be missed.

Very sensitive for acute hemorrhage

DAI is likely to be missed.

Defines nature of ICH* (ie, SDH, SAH)

Motion artifact may limit study.

Defines anatomic location of lesion

Posterior fossa lesions are poorly depicted.

Identifies fractures of the cranium

Depressed skull fractures at the vertex (or along the plane of an axial scan) are poorly depicted.

Sensitive to detecting intracranial air

The scanner has a weight limit, and a patient may be too heavy.

Sensitive in identifying foreign objects

A patient may decompensate while in the scanner.

*Intracranial hemorrhage.

Subdural hemorrhage.

Subarachnoid hemorrhage.

Computed tomography scans are helpful in assessing the degree of intracranial injury, in predicting outcomes, and, if findings are normal, in avoiding unnecessary hospitalization [54, 55] ; are very sensitive to acute hemorrhage or skull fracture; and aid in evaluating (1) intracranial hemorrhage, (2) skull fracture, (3) mass effect and midline shift, (4) obliteration of basal cisterns, and (5) evidence of herniation (subfalcine, tonsillar, or uncal).

Computed tomography scans cannot diagnose a concussion (which is a clinical diagnosis) and are poor for diagnosing DAI. If DAI has occurred, CT scans may show small hemorrhages in the corpus callosum and cerebral peduncles. In this case, an MRI of the brain should be obtained on an elective basis when the patient is clinically stable because no effective treatment of DAI is currently available. Magnetic resonance imaging is more sensitive for detecting brainstem injuries, posterior fossa lesions, and brain edema. For advantages and disadvantages of CT scanning in patients with closed head injury, see Table 3, above.

As a general rule, a repeat head CT scan is recommended within 4-8 hours of the initial scan for patients with intracranial hemorrhage and/or coagulopathy. [56, 57, 58] A repeat head CT scan is recommended sooner for patients who are deteriorating neurologically.

Spinal cord injury should be considered in patients with closed head injury and is present in up to 10% of these patients. [51] Accordingly, the cervical spine should be evaluated (with 3 views) during the initial evaluation. C1-C2 should be evaluated with a thin-cut CT scan in intubated patients. If any abnormalities are noted on initial cervical plain radiographs, this area should be further evaluated with a CT scan. Magnetic resonance imaging may be necessary to image a spinal cord injury. A rigid cervical collar (Philly) should remain on at all times while the patient is being evaluated.

One study found that CT angiography (CTA) findings used in addition to other screening criteria may help identify injuries not captured when conventional screening guidelines are followed. [59]

In a systematic review of the clinical utility of single photon emission CT (SPECT) for TBI, SPECT was shown to offer some advantages over CT and MRI for detection of mild TBI and to have excellent negative predictive value. Review authors suggest that this may be an important second test in settings where CT or MRI is negative after a closed head injury with post-injury neurologic or psychiatric symptoms. Abnormal regions most commonly revealed by SPECT in cross-sectional studies were the frontal (94%) and temporal (77%) lobes. SPECT was found to outperform both CT and MRI in acute and chronic imaging of TBI, particularly mild TBI. It was found to have near 100% negative predictive value. [60]

The findings of one study strongly suggest that diffusion tensor imaging (DTI), but not "classic" MRI sequencing, is a precise and accurate measurement tool for assessing a degree of brain injury after blunt trauma. Diffusion tensor imaging is a valuable research tool for furthering our understanding of pathophysiologic mechanism(s) evoked by blast injury and may become a prognostic tool. [61]

Henninger and colleagues found that in 136 patients 50 years of age or older admitted to a neurologic/trauma intensive care unit (ICU), preexisting leukoaraiosis (white matter hyperintensities) was significantly associated with poor outcomes at 3 and 12 months. According to study findings, the independent association between leukoaraiosis and poor outcomes remained when analysis was restricted to patients who survived up to 3 months, had moderate to severe TBI [enrollment Glasgow Coma Scale [GCS] ≤12; P = 0.001], or had mild TBI (GCS 13-15; P = 0.002), respectively. [62]

Meningeal enhancement on contrast-enhanced fluid-attenuated inversion recovery (FLAIR) images can help detect traumatic brain lesions and other abnormalities that are not identified on routine unenhanced MRI in symptomatic patients with mild TBI. Contrast-enhanced FLAIR MRI is recommended when contrast MRI is indicated for patients with symptomatic prior closed mild head injury.

In a study of 25 patients, 3 additional cases of brain abnormality were detected on contrast-enhanced FLAIR images. Meningeal enhancement was identified on contrast-enhanced FLAIR images in 9 cases, and other routine image sequences showed no findings of TBI. Overall, additional contrast-enhanced FLAIR images revealed more extensive abnormalities than were evident on routine images in 37 cases. [63]

Patients who arrive for treatment with decreased GCS score and normal findings on head CT may have another condition that needs to be considered, such as one of the following:

  • Acute ischemic stroke (within 24 hours) that is not seen on head CT scan

  • Postictal state

  • Spinal cord injury

  • Intoxication or effects of illicit drug use

    • Substance use disorder has been associated with TBI and has significant implications for post-TBI recovery and rehabilitation.
    • Understanding the complex relationship between TBI and substance misuse enhances the clinical treatment of individuals with these 2 highly comorbid conditions. [35]
  • Prior medical conditions (speaking with family members may help in differentiating an acute from a chronic condition)
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Procedures

Patients with severe brain injury (GCS score < 8), those who have labile blood pressure, those who require intensive care monitoring, and those who need surgical intervention are likely to require placement of an indwelling urinary catheter (Foley), placement of a central venous access catheter, and invasive blood pressure monitoring via an arterial line.

Intracranial pressure monitoring in patients with closed head injuries is a matter of controversy; however, most authors agree that invasive ICP monitoring is warranted for patients with a GCS score of 8 or less and an abnormal CT scan finding, for patients with suspected severe brain edema, and for those with ICP that is suspected to be significantly elevated.

Data from ICP monitoring can supplement a reliable neurologic examination, and this can be crucial for patients whose examination findings are affected by sedatives, paralytics, and other factors. Patients who have an abnormal head CT scan, a GCS score of 8 or less, or both, and who require emergent surgery on another organ system should be considered for some form of ICP monitoring before going to the operating room (or perhaps while in the operating room) because frequent neurologic examinations are not possible in this setting.

Intracranial pressure monitoring can be performed with an intraventricular catheter or with an intracranial fiberoptic monitor (Camino). Either procedure provides adequate ICP monitoring. The intraventricular catheter is preferred for closed head injuries when the ventricles are large enough to accommodate a catheter. The advantage of the catheter is its ability to drain CSF if ICP is elevated (>20 mm Hg), although ventricles compromised by mass effect make draining of much CSF difficult. An accurate pressure reading can be lost if the ventricle collapses around the catheter tip during drainage.

The advantage of the fiberoptic catheter is that ICP can be monitored for patients who have very small ventricles into which ventriculostomy catheters cannot be inserted. Pressure measurements are not prone to fluctuations in ventricular size.

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