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NE.RVOUS SYSTEM
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Lumbar PUllcture
A lumbar puncture (LP) is the collection of CSF from a needle placed
into the subarachnoid space below the Ll vertebra, usually between
L3 and L4. The patient is placed in a side-lying position with the neck
and hips flexed as much as possible (to open the laminae for the best
access to the subarachnoid space). Multiple vials of CSF are collected
and tested for color, cytology, chlorine, glucose, protein, and pH. The
opening and closing pressures are noted. LP is used to assist in the
diagnosis of autoimmune and infectious processes, and, in certain circumstances, it is used to verify subarachnoid hemorrhage (SAH). LP
provides access for the administration of spinal anesthesia, intrathecal
anribiotics, or for therapeuric CSF removalYL2J
Clinical Tip
Headache is a common complaint after an LP secondary
to meningeal irritation or CSF leakage. A patient may be
placed on bed rest for several hours after an LP to minimize upright positioning, which increases headache. Other short-term complications of LP include backache, bleeding
at the needle site, voiding difficulty, and fever.
Positroll Emissioll Tomography
Positron emission tomography (PET) produces three-dimensional
cross-section images of brain tissue after the injection of nuclide
positrons that produce gamma rays and are detected by a scanner.
This physiological image measures cerebral glucose uptake, oxygen
metabolism and blood flow." A PET scan may be best used to assist
in the diagnosis of cerebrovascular disease or trauma, epilepsy,
dementia or psychiatric disorders.
Electroellcepbalograpby
Electroencephalography is the recording of electrical brain activity,
using electrodes affixed to the scalp at reSt or sleep, after sleep deprivation, after hyperventilation, or after photic stimulation. Brain
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ACUTE CARE HANDBOOK FOR I}HYSICAL THERAPISTS
waves may show abnormalities of activity, amplitude, pattern, or
speed. Electroencephalography is used in conjunction with other neurodiagnostic tests to assess seizure focus, sleep and metabolic disorders, dementia, and brain death.14•23
Evoked Pote"tials
Evoked potentials are electrical responses generated by the stimulation of a sensory organ. A visual evoked potential is measured using electrodes that are placed over the occipital lobe to record occipital
cortex activity after a patient is shown nashing lights or a checkerboard pattern. Visual evoked potentials are used to assess optic neuropathies and opric nerve lesions. A brain stem auditOry evoked response is measured using electrodes that are placed over the vertex
to record CN VIII, pons, and midbrain activity after a patienr listens
to a series of clicking noises through headphones. Brain stelll auditOry
evoked responses are used to assess acoustic tumors, brain stem
lesions in multiple sclerosis (MS), or brain srem function (in comatOse
parienrs). A somatosensory evoked potential is measured using electrodes over the contralateral sensory cortex after the median or posterior tibial nerve is electrically stimulated. Somatosensory evoked potentials are used to assess SCI, cervical disc disease, sensory dysfunction associated with MS, or parietal cortex rumor.14•23
Electromyography a"d Nerve COl/dllctio" Velocity Stlldies
Electromyography (EMG) is the recording of muscle activity at rest,
with voluntary movement, and with electrical stimulation with needle electrodes. Nerve conduction velocity studies are the measuremenr of the conduction time and amplitude of an electrical stimulus along a peripheral nerve(s). EMG and nerve conduction velocity
studies are used to assess and differentiate myopathy and peripheral
nerve injury, respectively. 14
Myelography
Myelography uses x-ray to show how a contraSt medium nows
through the subarachnoid space and around rhe vertebral column
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after the removal of a small amount of CSF and the injection of dye
via LP. It is used ro assess bone displacement, disc herniation, cord
compression, or tumor. 14,2j
Clinical Tip
Depending on the rype of dye used, a patienr may have
positioning restrictions after a myelogram. I f water-based
dye was used, the patient should remain on bed rest with
the head of the bed at 30 degrees for approximately 8-24
hours, because the dye may cause a seizure if it reaches the
cranium. If an oil-based dye was used, the patienr may
have to remain in bed with the bed flat for 6-24 hours.
Additionally, the patient may experience headache, back
spasm, fever, nausea, or vomiting, regardless of the type of
dye used B
Pathophysiology
Traumatic Brai" I"jury
The medical-surgical treatmenr of traumatic brain injury (TBI) is a
complex and challenging task. Direct or indirect trauma to the skull,
brain, or both typically results in altered consciousness and systemic
homeostasis. TBI can be described by the foliowingK
1 .
Location. TBI may involve damage to the cranium only, the
cranium and brain structures, or brain structures only. Frequently,
head trauma is categorized as ( 1 ) closed (protective mechanisms are
maintained), (2) open (protective mechanisms are altered), (3) coup
(the lesion is deep to the site of impact), (4) conrrecoup (the lesion is
opposite the site of impact), or (5) coup-contrecoup (a combination
of coup and contrecoup).
2.
Extent. TBI may be classified as primary (in reference to the
direct biomechanical changes in the brain) or secondary (in reference to the latent intracranial or systemic complications that exacer-
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AClJfE CARE HANDBOOK FOR PIIYSICAI THERAPISTS
bate the original injury). The terms focal and diffuse are often used
to describe a specific or gross lesion, respectively.
3.
Severity. In addition to diagnostic tests, TBI may be classi-
fied according to cognitive skill deficit and GCS as mild ( 1 3- 1 5),
moderate (9-1 2), or severe (3-8 ) .
4 .
Mechanism o f injury. The two mechanisms re ponsible for
primary TBI are acceleration-deceleration and rotation forces. These
forces may be of low or high velocity and result in the compression,
traction, or shearing of brain structures.
Secondary brain injury occurs within minutes to hours of the traumatic primary injury and is characterized by inflammatory, vascular, and biomolecular abnormalities. These changes include the release of