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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