Common TBI Testing

Identifying Brain Injuries

Clearly the most exciting area of advancement in the diagnosis of traumatic brain injury involves neuro imaging. At its most basic, neuro imaging covers two broad categories: (1) brain structure; and (2) brain function.

Analyzing brain structure is very different from analyzing brain function. When looking at brain structure, it is the anatomy of the brain that is analyzed. In order this point be understood, were an individual who immediately died be placed in a scanning device which looks only at brain structure, and lest significant deterioration of the brain immediately occurred, one could expect the scan to be read as “normal.” (This to be compared to a devise scanning for brain function which obviously would demonstrate “no function,” thus extremely abnormal).

However, were there to be a trauma to the brain itself, which trauma caused bleeding within the skull, or contusions to the brain, or bleeding within the skull cavity, then a devise measuring brain structure could be expected to show the abnormality, depending on amount of damage.

Tests analyzing brain function are not nearly as concerned with the actual structural environment of the brain as much as they are concerned with brain function itself. We first discuss those devices or tests which analyze brain structure:

Some of the imaging tests which analyze brain structure include the following:

  • Skull X-Ray;
  • Computed Tomography (CT);
  • Magnetic Resonance Imaging (MRI);
  • Diffusion Tensor Imaging (DTI);
  • Magnetization Transfer Imaging (MTI);
  • Magnetic Resonance Spectroscopy (MRS);
  • Magnetic Source Imaging (MSI);

Neuro Imaging: Computed Tomography (CT)

Since its introduction in approximately 1973, computed tomography (CAT, or CAT computed axial tomography) has developed quickly. A series of collimated x-ray beams through the tested body and measurement of the extent of tissue absorption is made. CT is demonstrative of collections of blood (hematomas), cerebral contusions (bruises), edema (swelling), as well as basal skull fractures.

Neuro Imaging: Magnetic Resonance Imaging (MRI)

MRI is a diagnostic procedure which examines body tissue by subjecting the atomic nuclei of the tissues to a magnetic field. The atomic nuclei of the tissues are stimulated by the field. Bad tissue responds differently than good.

In recent years, huge advances have occurred with respect to MRI. Up until approximately 2000, most neuro imaging centers maintained MRI machines with Tesla field strength 1 to 1.5 magnets. As of recent, the FDA has approved Tesla field strength 3 magnets for human use. With the use of Tesla field strength 3 magnets, lesions are now being seen on MRI that were impossible to detect on the earlier MRI scanners using lesser field strength magnets. Advancements in software utilized by the MRI scanners have likewise improved their diagnostic capability.

Where head injury is concerned, Gradient Echo software has proved extremely valuable. Many teaching institutions are now experimenting with field strength magnets as high as Tesla 10. It is expected that with the advances in MRI technology, even extremely mild traumatic brain injury patients will have demonstratively viewable abnormality on MRI.

An example of this was capitalized on by the Scarlett Law Group during the case of Rasmussen versus Shade. Mr. Rasmussen had been rear ended while in stopped traffic in Northern California. There was less than $500 damage to the rear bumper of Mr. Rasmussen´s vehicle. Nonetheless, Mr. Rasmussen sustained a traumatic brain injury.

Following the accident, imaging was done on a T-1 magnet strength MRI scanner in the Sacramento area. The MRI scanner was read as “normal”. Several months later, imaging was again done on the T-1 scanner. It too was read as “normal”.

After contacting the Scarlett Law Group, treating physicians ordered a repeat MRI, but this time utilizing a T-3 scanner. Two focal lesions in the anterior and posterior frontal lobes were immediately seen. Given the coup/contra coup pattern of the lesions, and further given their presence at the juncture of the grey/white matter of the brain, diagnoses of traumatic brain injury was conclusively made.

What is unique about this is that in utilizing the lesser strength scanner, the lesions were not read on the film. However, after looking at the T-3 film, and comparing it to the film derived from the lesser strength MRI scanner, the abnormalities of the lesions could be vaguely made out. In other words, no one could have been critical of the earlier readings of the film from the lesser strength scanners as the lesions were not readily apparent. However, with the benefit of the T-3 film, the abnormalities could be seen on the earlier scans though not with the absolute clarity of the T-3 film.

Where head injury is concerned, it is thought that the admission of the T-3 film into evidence in the Rasmussen versus Shade case is the first time a California court (and jury), has had the benefit of said technology. It is expected to be the norm in years to come.

Neuro Imaging: Diffusion Tensor Imaging (DTI)

Diffusion tensor imaging is an MRI application that utilizes the diffusion of water model molecules for imaging the brain. DTI not only measures the diffusion of water molecules in a particular direction, but can analyze by imaging diffusion in as many as six or more directions. This allows for a three dimensional matrix or calculation of “tensor”. Structural integrity in the white matter of the brain can be measured as water diffusion is higher along fiber tracks then across them.

Neuro Imaging: Magnetization Transfer Imaging (MTI)

Magnetization transfer imaging (MTI) is another technique that increases the contrast between tissues by exploiting the exchange of protons between water and macromolecules. A radio frequency pulse selectively saturates protons that are bound to macromolecules in the brain. MTI provides information about tissue changes not detected by T1 or T2 MRI. MTI has yet to be extensively used in the area of traumatic brain injury.

Neuro Imaging: Magnetic Resonance Spectroscopy (MRS)

Magnetic Resonance Spectroscopy detects signals from individual solutes in body tissues thereby offering neuro chemical information about the brain. MRS is generally used to assess metabolic irregularities following brain injury. It is based on measuring magnetic signals from certain nuclei in response to radiofrequency pulses. MRS correlates well with neuropsychological functioning and functional outcome tests.

Neuro Imaging: Magnetic Source Imaging (MSI)

Magnetic source imaging (MSI) utilizes magnetoencephalographic technology to acquire electrophysiological data from the brain and combine it with structural data from conventional MRI technology. MSI technology is new. It holds hope in the diagnoses of mild TBI patients with post-concussive syndromes.

Generally speaking, structural imaging is extremely helpful in cases involving skull fractures as well as hematomas, or hemorrhages which may occur at a variety of locations in the brain.

Common hematomas include:

  1. Epidural Hematomas – This injury forms when the brain´s outer covering, or dura, is stripped away from the skull by blood from lacerated blood vessels or bleeding from a fracture. The injury generally occurs over the temporoparietal area but can also occur in the frontal lobes as well as the other areas of the brain.
  2. Subdermal Hematomas – This injury forms in the space between the dura and brain, often produced by torn veins on the brain surface and the inside edge of the dura matter. This injury may develop within the first 24 hours of insult, but and develop up to two weeks are after insult.
  3. Intracerebral Hematomas – This injury forms within the substance of the brain and often results from a laceration. Often occurring in the frontal and temporal lobes, the injury has also been found in the basal ganglia and cerebellum.
  4. Extradural Hematomas – This injury involves a collection of blood outside the dura between the inter-table of the skull and the dura.

Note that even more damage to the patient can occur as a result of secondary damage due to the continuous process of the initial insult. Intracranial pressure caused by ongoing hematomas can be more damaging than the initial insult to the brain itself. Where cerebral blood flow is cut off, without relief, death results.

As contrasted with the devices/tests which analyze brain structure, discussed above, the following are utilized in order to quantify and measure brain function:

  • Functional MRI (fMRI);
  • Positron Emission Tomography (PET);
  • Single Photon Emission Computed Tomography (SPECT)

Neuro Imaging: Functional MRI (fMRI)

Functional MRI is gaining wide use as a neuro imaging technique for measuring brain function. The test operates under the assumption that an increase in neuronal activity results in an increase in local blood flow leading to reduced concentrations of deoxy- hemoglobin, a product of oxygen consumption. This concept is widely known as blood-oxygen-level-dependent (BOLD). fMRI is particularly effective in moderate to severe TBI as studies of working memory on these patients suggest blood flow abnormalities relative to comparison subjects, particularly in the frontal lobes.

Neuro Imaging: Positron Emission Tomography (PET)

Positron emission tomography uses very short-lived radioactive isotopes of elements commonly used in brain metabolism (glucose), and then shows an image which represents not only brain structure but also brain function (i.e., how the glucose is used). Positron emission tomography shows that language happens in a parallel array, and that the brain simultaneously processes in several areas at once as opposed to serially. In essence, PET is a diagnostic imaging technique for measuring regional brain metabolism. The clinical uses of PET scanning include brain injury evaluation; organic brain dysfunction; Parkinson´s disease; epilepsy lesion location in pre-surgical evaluation; cerebrovascular disease (stroke) and assessment of recovery; differential diagnosis of Alzheimer´s disease and other memory disorder; and differential diagnosis of brain tumor and radiation treatment. Even where there is no abnormality found on MRI or CT scan, PET scans have shown abnormality consistent with postconcussive syndrome and mild TBI. In most jurisdictions, however, the abnormality found on PET must be correlated with neuropsychological testing before it becomes admissible in court.

Neuro Imaging: Single Photon Emission Computed Tomography (SPECT)

Single photon emission tomography is another generation of cerebral nuclear scans. It is commonly used for the study of circulation and perfusion of the brain. It is a computer-an enhanced version of a brain scan. It produces regional maps of the distribution of radioactively-labeled tracers in the brain with more resolution than traditional brain scans but without the cost of PET.

While not conclusive, these tests have provided validation for neuropsychological assessments and in the setting of the courtroom may provide the jurors with a picture of the invisible injury.

If you or someone you know has been injured or suffered Traumatic Brain Injury or TBI, you need the assistance of the Scarlett Law Group. Call (415) 688-2176 today to speak with member of our legal team. Our San Francisco injury attorneys are available to help you learn more about your rights and options.

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