Use of neuroimaging in rehabilitation

Abstract:

This chapter provides an overview of the use of neuroimaging in rehabilitation. As relates to patients with neurological injuries (e.g., brain injury or stroke) and dysfunction (e.g., Parkinson disease or hereditary disorders), therapists should be able to interpret images of the nervous system to better understand how the neural insult and medical procedures affect movement and function in daily life. Expert analysis of neuroimaging using differential diagnosis skills and knowledge of neuroanatomy is critical in order for these professionals to know when to refer a patient to another health care practitioner, when to refer and treat, when to merely treat, and when to neither refer nor treat.

Keywords:

computed tomography (CT), magnetic resonance image (MRI), diffusion tensor imaging (DTI), radiograph, diagnostic imaging, functional imaging

Objectives

After reading this chapter the student or therapist will be able to:

1.

Identify conventional and advanced neuroimaging techniques.
2.

Classify the different neuroimaging techniques into structural and/or functional imaging techniques.
3.

Describe strengths and weaknesses of different neuroimaging techniques.
4.

Recognize various slices of the central nervous system; what nuclear masses are visible in that slice; how the ventricles change from one slice to another; and how sagittal, horizontal, and coronal slices present those nuclear masses and/or ventricles differently.
5.

Recognize the difference in diagnostic capabilities of radiography, computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine scans.
6.

Describe images using the correct neuroradiological descriptive terminology.
7.

Recognize normal and abnormal neuroanatomy on CT scans and MRI images.
8.

Analyze information obtained from imaging of the central nervous system and integrate this information into the neurological clinical presentation and the patient’s intervention.
9.

Recognize and analyze how neuroimaging may and may not be reflected in the movement diagnosis made by a physical or occupational therapist.
10.

Summarize relevance of neuroimaging to rehabilitation and patient care.

Direct access practice for physical therapists in several states of the United States has increased the role of these professionals as primary care providers engaged in value-based and patient-centered care for improving mobility outcomes. Physical therapists are now part of the emergency department, sometimes serving to triage, and manage patients with nonsurgical musculoskeletal disorders. Physical therapists serving in the military, Public Health Service, Indian Health Service, Veterans Health Administration, Bureau of Prisons, and health care organizations, such as Georgetown University Hospital, Kaiser-Permanente, Northern California, now have imaging privileges. Expanding roles have made it particularly important for therapists to recognize the need of diagnostic imaging and analyze diagnostic imaging for improving patient care and decisions related to patient care.

As relates to patients with neurological injuries (e.g., brain injury or stroke) and dysfunction (e.g., Parkinson disease or hereditary disorders), therapists should be able to interpret images of the nervous system to better understand how the neural insult and medical procedures affect movement and function in daily life. Expert analysis of neuroimaging, using differential diagnosis skills and knowledge of neuroanatomy, is critical in order for these professionals to know when to refer a patient to another health care practitioner, when to refer and treat, when to merely treat, and when to neither refer nor treat.

Entry-level knowledge of content such as pharmacology, radiology, and medical screening has become an accreditation requirement for doctoral education programs in physical and occupational therapy. Orthopedic radiology is now a common part of curricula; however, content on neuroradiology, more specifically the application of neuroradiology in practice, is lacking. In a study by Little and Lazaro, it was found that many of the physical therapy practitioners in California use medical imaging in their practice. When inquired about the types of imaging, the majority of respondents felt comfortable using results (and radiology reports) from radiographs obtained because of a musculoskeletal problem. This study showed the lack of access to and confidence in using medical images of the central nervous system (CNS).

In certain instances, it may be easier for therapists to recognize musculoskeletal problems when viewing radiographic images because the abnormality in the structure directly correlates with the orthopedic movement problem. When images of the CNS are viewed, correlations with movement system disorders may be much more complex, requiring knowledge of neuroanatomy, such as relationship of nuclei, tract systems, and basic neurochemistry. For example, when looking at a bone fracture ( Fig. 37.1 A) versus a vascular insult (see Fig. 37.1 B), it is clear that the fracture and its effects on the bone, muscle, or skin can easily be visualized and interpreted. The second image of the CNS has many surrounding structures that must be identified in relation to the vascular insult. Good knowledge of neuroanatomy and neuroimaging is therefore essential for adopting imaging in PT practice.

In 2007, the journal Physical Therapy produced a special issue on neuroradiology in physical therapy practice. It is encouraging to note that this issue offered physical therapy clinicians an opportunity to understand the modalities used in the imaging of the brain and the spinal cord (for details, see the article by Kimberley and Lewis ). However, the rest of the article presented the application of neuroradiology in physical therapy research, ^, and although these articles provided valuable information for the practicing clinician, the articles did not specifically give insights as to how clinicians can use the knowledge of neuroradiology in their actual patient/client management.

It has been known for a long time that physical therapy interventions improve function by making new neural connections or by unmasking the neural networks that were previously dormant. Though not a common practice in patient care, the advent of functional neuroimaging techniques has made it possible to study the benefits of the therapy and has opened more ways to guide clinical practice. Some of the benefits that therapists may have with current neuroimaging methods include being able to (1) assess the changes with therapy, (2) make treatment plans appropriate for patient by correlating clinical symptoms with neuroimaging results, (3) assess prognostic implications, (4) provide family and patient education, and (5) develop appropriate goals and accordingly develop treatment plans.

Visualizing the central nervous system

Before jumping into viewing images of the nervous system, the reader needs to be very familiar with the position and type of slices presented in those images. Fig. 37.2 illustrates the three types of slices common to the nervous system. The horizontal slices shown in Fig. 37.3 are cuts made horizontally through the brain beginning with a superior slice at the level of the beginning of the lateral ventricles. This individual would be lying supine if the brain was cut as shown. If a person were standing, the horizontal slice would be horizontal to the ground with the frontal lobes facing forward (toward the nose) and the occipital lobe in the back. The slices cut horizontally are always perpendicular to the brain stem and spinal cord or perpendicular to the upright position of the brain regardless of the position of the head in space. All right and left slices will look exactly the same as long as the nervous system has not sustained any insult. Fig. 37.4 shows the position of an upright human and what the skeleton would look like in the same position. Can you visualize what the horizontal slices would look like? The horizontal section would be perpendicular to this upright position. When viewing radiological slices in horizontal, the slices will often be on a slight angle with the lower portion slightly forward. Most of these films are taken when individuals are supine, which places the brain off vertical so a correction is made. The film usually slices horizontally through the brain as if the head were slightly tucked, similar to the image of the adult in Fig. 37.4 A . Also, some radiologists want a slightly different angle to the slice because they are looking for specific orientations. When viewing these films, try to look at the radiological slice pattern (scanogram), if shown. Fig. 37.3 shows a progression of horizontal slices as if the individual were supine and the slices began anteriorly with emphasis on ventricular changes as part of the progression. Many of the medical images of the brain are viewed as horizontal (or axial) slices or views. The person is lying supine when undergoing computed tomography (CT), magnetic resonance imaging (MRI), or positron emission tomography (PET). Therefore the imaging process cuts 90 degrees off the horizontal plane of earth in order to achieve horizontal slices of the brain. Remember to look at the scanogram, if available, to identify the position of the head in relation to the cuts.

Coronal slices in the right hemisphere look similar to those in the left hemisphere except that the top of the slice will not look like the bottom on either side (see Fig. 37.2 ). The two sides will reflect each other, with the tops being alike as well as the bottoms. Depending on where the cut is made, the result will be cortex on the outside, tracts (white matter) projecting downward, and gray matter again inferior and medial within the slices as the thalamus, basal ganglia, caudate, hippocampus, and so on are viewed. These slices begin at the top and cut down through both sides of the brain, with the slice ending on the inferior section. The progression of the slides can go from front (frontal lobe) to back (occipital lobe) or back to front. If visualized in a standing subject, the slice would begin in the superior frontal area and slice downward through the brain toward the feet, thus cutting equally on both sides. These slices can proceed in the posterior (backward) direction of the brain but always cutting from the top toward the bottom with equal distribution on each side. Fig. 37.5 progresses from the front of the brain toward the back using the ventricles as a point of reference.

For sagittal cuts (see Fig. 37.2 ), most cuts start by slicing down through the central fissure separating both sides of the brain. This cut is called a midsagittal section. Each sagittal slice proceeds outward toward the lateral aspect of the brain on each side respectively, depending on which side is being sliced. Anatomically, you begin as if you were slicing down through the middle of the face and the back of the head when a person is standing. Each sagittal slice moves from the inside outward toward the ear or laterally away from the midsagittal slice. Each slice cuts though the front and back of the brain from top to bottom and proceeds from medial to lateral. Sagittal images usually begin on either the right or the left side and continue slicing toward the middle to the midsagittal section separating the two sides of the brain, and then proceed toward the outside on the opposite side of the brain from the beginning slice.

Another way to conceptualize the nervous system is by visually sequencing from a view of a human in a specific position to the skeleton of a human in that position to an intact plastinated nervous system in that same position. The reader is encouraged to try to visualize what the horizontal, coronal, and sagittal slices might look like given the spatial position of the individual. Once you can easily recognize the various types of slices and where the slice was made when viewing the nervous system, you are ready to begin viewing radiological images.

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