Closed Head Injury Workup

Updated: Feb 24, 2016
  • Author: Leonardo Rangel-Castilla, MD; Chief Editor: Brian H Kopell, MD  more...
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Workup

Laboratory Studies

Lab studies include the following:

  • CBC count 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 on anticonvulsant medications to ensure therapeutic levels

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Imaging Studies

CT scanning of the head is the criterion standard for patients with acute closed head injuries. [16] A head CT scan is warranted, except for patients with only minor head trauma who are neurologically intact and 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 the Head Trauma Evaluation

Table. (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 anatomical 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

 

CT scans are helpful in assessing the degree of intracranial injury, in predicting outcome, and, if findings are normal, in avoiding unnecessary hospitalization. [47, 48] CT scans are very sensitive to acute hemorrhage or skull fractures. CT scans aid in evaluating (1) intracranial hemorrhage, (2) skull fractures, (3) mass effect and midline shift, (4) obliteration of the basal cisterns, and (5) evidence of herniation (subfalcine, tonsillar, or uncal).

CT 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. MRI 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 injuries, see Table 3.

As a general rule, a repeat head CT scan is recommended within 4-8 hours of the initial scan in patients with intracranial hemorrhages and/or coagulopathies. [49, 50, 51] A repeat head CT scan is recommended sooner in patients who are deteriorating neurologically.

Spinal cord injuries should be considered possible in patients with closed head injuries. Spinal cord injuries are present in up to 10% of these patients. [45] 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 the initial cervical plain radiographs, this area should be further evaluated with a CT scan. An MRI 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.

The results of one study found that computed tomographic angiography (CTA) findings used in addition to other screening criteria may help identify injuries not captured using conventional screening guidelines alone. [52]

In a systematic review of the clinical utility of single photon emission CT (SPECT) for TBI, SPECT was shown to have some advantages over CT and MRI in the detection of mild TBI and to have excellent negative predictive value. The authors suggest it may be an important second test in settings where CT or MRI are negative after a closed head injury with post-injury neurologic or psychiatric symptoms. The most commonly abnormal regions revealed by SPECT in cross-sectional studies were frontal (94%) and temporal (77%) lobes. SPECT was found to outperform both CT and MRI in both acute and chronic imaging of TBI, particularly mild TBI. It was also found to have a near 100% negative predictive value. [53]

The findings of one study strongly suggest that diffusion tensor imaging (DTI), but not "classic" MRI sequences, is a more precise and accurate measurement to assess a degree of brain injury after blunt trauma. DTI is a valuable research tool to further the understanding of pathophysiological mechanism(s) evoked by blast injury and may become a prognostic tool. [54]

Henninger et al found that in 136 patients 50 years or older who were admitted to a neurologic/trauma ICU, preexisting leukoaraiosis (white matter hyperintensities) was significantly associated with a poor outcome at 3 and 12 months. According to the study findings, the independent association between leukoaraiosis and poor outcome remained when the 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. [55]

According to one study, 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 traumatic brain injury. The authors therefore recommended contrast-enhanced FLAIR MR imaging when a contrast MR study is indicated in patients with symptomatic prior closed mild head injury. In a study of 25 patients, 3 additional cases of brain abnormality were detected with the contrast-enhanced FLAIR images. Meningeal enhancement was identified on contrast-enhanced FLAIR images in 9 cases, while the other routine image sequences showed no findings of traumatic brain injury. Overall, the additional contrast-enhanced FLAIR images revealed more extensive abnormalities than routine imaging in 37 cases. [56]

Patients who arrive with a decreased GCS and normal findings on head CT scans may have another condition that needs to be considered. These include the following:

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

  • Postictal state

  • Spinal cord injury

  • Intoxication or effects of illicit drug use

  • Prior medical conditions (Speaking with family members may help in differentiating acute from chronic conditions.)

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Other Tests

Order serum sodium, urine specific gravity, urine osmolarity, and serum osmolarity tests for individuals with urine output of 250 mL/h or more for 3 or more consecutive hours (pediatric patients, >3 mL/kg/h) and for patients who are thought to have diabetes insipidus. Large doses of mannitol can mask diabetes insipidus by producing a high urine output.

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Procedures

Patients with a 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 the placement of an indwelling urinary catheter (Foley), placement of a central venous access catheter, and invasive blood pressure monitoring via an arterial line.

ICP monitoring in patients with closed head injuries is a matter of controversy; however, most authors agree that invasive ICP monitoring is warranted in patients with a GCS score of 8 or less and an abnormal CT scan finding, in patients with suspected severe brain edema, or in any situation in which the ICP is suspected to be significantly elevated. The ICP offers data that supplement a reliable neurological examination and can be crucial in patients whose examination findings are affected by sedatives, paralytics, and other factors.

  • Patients with an abnormal head CT scan finding, a GCS score of less than 8, or both who require emergent surgery on another organ system should also be considered for some form of ICP monitoring before going to the operating room (or perhaps in the operating room) because frequent neurological examinations are not possible in this setting.

  • ICP monitoring can take 1 of 2 forms, either as an intraventricular catheter or an intracranial fiberoptic monitor (Camino).

    • The intraventricular catheter is preferred in closed head injuries when the ventricles are large enough to accommodate a catheter. The advantage of the catheter is the ability to drain CSF if the ICP is elevated (>20 mm Hg), although ventricles compromised by mass effect make draining 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 in patients who have very small ventricles, in whom ventriculostomy catheters cannot be inserted. The pressure measurements are not prone to fluctuations in ventricular size. Either procedure provides adequate ICP monitoring.

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