uncal herniation


Also found in: Dictionary, Thesaurus.

herniation

 [her″ne-a´shun]
abnormal protrusion of an organ or other body structure through a defect or natural opening in a covering membrane, muscle, or bone. (See also hernia.)
Herniation syndromes. From Ignatavicius and Workman, 2002.
caudal transtentorial herniation transtentorial herniation.
central herniation a downward shift of the brainstem and the diencephalon due to a supratentorial lesion, causing Cheyne-Stokes respirations with pinpoint nonreactive pupils.
cingulate herniation a shift of the cingulate gyrus to below the falx cerebri.
disk herniation (herniation of intervertebral disk) (herniation of nucleus pulposus) herniated disk.
tentorial herniation transtentorial herniation.
tonsillar herniation protrusion of the cerebellar tonsils through the foramen magnum.
transtentorial herniation downward displacement of medial brain structures through the tentorial notch by a supratentorial mass, exerting pressure on the underlying structures, including the brainstem; this is a life-threatening situation because of pressure on the third cranial nerve, with symptoms including dilated, nonreactive pupils, ptosis, and a decreased level of consciousness. Called also caudal transtentorial herniation, tentorial herniation, and uncal herniation.
uncal herniation transtentorial herniation.

cau·dal trans·ten·to·ri·al her·ni·a·tion

displacement of medial temporal structures through the incisura, with or without rostrocaudal brainstem shift.
Synonym(s): uncal herniation

uncal herniation

Brain herniation, herniation syndrome, transtentorial herniation Neurology A condition in which the uncus–the anterior hooked end of the parahippocampal gyrus on the basomedial surface of the temporal lobe of the brain is displaced due to ↑ intracranial causing progressive brain and brainstem damage Etiology Cerebral edema due to head injury, space-occupying lesions–primary and metastatic brain tumors or other lesions within the skull, bacterial meningitis; UH compresses cranial nerve III, the midbrain, and the posterior cerebral artery, leading to coma and respiratory arrest. Cf Cerebellar herniation.

herniation

(her-ne-a'shun)
The displacement of body tissue through an opening or defect.

cerebral herniation

Downward displacement of the brain (usually as a result of cerebral edema, hematoma, or tumor) into the brainstem. The resulting injury to brainstem functions rapidly leads to coma, nerve palsies, and death if treatment is ineffective.
Enlarge picture
HERNIATED DISK
Enlarge picture
NORMAL AND HERNIATED SPINAL DISKS

herniation of nucleus pulposus

Prolapse of the nucleus pulposus of a ruptured intervertebral disk into the spinal canal. This often results in pressure on a spinal nerve, which causes lower back pain that may radiate down the leg, a condition known as sciatica. illustration;

Patient care

A history is obtained of any unilateral low back pain that radiates to the buttocks, legs, and feet. Almost all herniations occur in the lumbar and lumbosacral region; 8% in the cervical region and only 1% to 2% in the thoracic region. When herniation follows trauma, the patient may report sudden pain, subsiding in a few days, then a dull, aching sciatic pain in the buttocks that increases with Valsalva's maneuver, coughing, sneezing, or bending. The patient may also complain of muscle spasms accompanied by pain that subsides with rest. The health care professional inspects for a limited ability to bend forward, a posture favoring the affected side, and decreased deep tendon reflexes in the lower extremity. In some patients, muscle weakness and atrophy may be observed. Palpation may disclose tenderness over the affected region. Tissue tension assessment may reveal radicular pain from straight leg raising (with lumbar herniation) and increased pain from neck movement (with cervical herniation). Thorough assessment of the patient's peripheral vascular status, including posterior tibial and dorsalis pedis pulses and skin temperature of the arms and legs, may help to rule out ischemic disease as the cause of leg numbness or pain.

The patient is prepared for diagnostic testing by explaining all procedures and expected sensations. Tests may include radiographic studies of the spine (to show degenerative changes and rule out other abnormalities), myelography (to pinpoint the level of herniation), computed tomography scanning (to detect bone and soft tissue abnormalities and possibly show spinal compression resulting from the herniation), magnetic resonance imaging (to define tissues in areas otherwise obscured by bone), electromyography (to confirm nerve involvement by measuring the electrical activity of muscles innervated by the affected nerves), and neuromuscular testing (to detect sensory and motor loss as well as leg muscle weakness).

Pain and its management are often crucial elements of care; levels of pain are monitored, prescribed analgesics are administered, the patient is taught about noninvasive pain relief measures (such as relaxation, transcutaneous nerve stimulation, distraction, heat or ice application, traction, bracing, or positioning), and the patient's response to the treatment regimen is evaluated. During conservative treatment, neurological status is monitored (esp. in the first 2 to 3 weeks after beginning treatment) for signs of deterioration, which may indicate a need for surgery. Neurovascular assessments of the patient's affected and unaffected extremities (both legs or both arms) are performed to check color, motion, temperature, sensation, and pulses. Vital signs are monitored, bowel sounds are auscultated, and the abdomen is inspected for distention. The disorder and the various treatment options are explained to the patient, including bedrest and pelvic (or cervical) traction, local heat application, a physical therapy designed exercise program, muscle-relaxing and anti-inflammatory drug therapy, injection of local anesthetic and steroid drugs, acupuncture, and surgery.

Both the patient and family are encouraged to express their concerns about the disorder; questions are answered honestly, and support and encouragement are offered to assist the patient and family to cope with the frustration of impaired mobility and the discomfort of chronic back pain. The patient is encouraged to perform self-care to the extent that immobility and pain allow, to take analgesics before activities, and to allow adequate time to perform activities at a comfortable pace.

Walking and gentle stretching are encouraged as part of daily exercise during conservative therapy. If the patient is restricted to bedrest (or in traction), the patient should increase fluid intake and use incentive spirometry to avoid pulmonary complications. Skin care and a fracture bedpan are provided if the patient is not permitted bathroom or commode privileges.

For patients who require surgery, the patient is prepared physically and psychologically for the specific procedure (laminectomy, spinal fusion, microdiskectomy) and postoperative care regimen, and informed consent is obtained. The patient may donate blood prior to surgery for later autotransfusion as needed.

Postoperative Care: Bedrest is enforced for the prescribed period, the blood drainage system in use is managed, and the amount and color of drainage are documented. Any colorless moisture or excessive drainage should be reported; the former may indicate cerebrospinal fluid leakage. A log-rolling technique is used to turn the patient from side to side, and the patient is taught how to turn in this manner when moving about or getting up from bed at home. Analgesics are administered as prescribed, esp. 30 min before early attempts at mobilization. The health care professional assists the patient with prescribed mobilization. Depending on the surgery required, the patient may require a back brace (individually fitted) for a period of time after surgery, and this is carefully fitted and the patient taught about its use.

Before discharge, proper body mechanics are reviewed with the patient: bending at the knees and hips (never the waist), standing straight, and carrying objects close to the body. The patient is advised to lie down when tired and to sleep on the side or back (never on the abdomen) on an extra-firm mattress or a bed board. All prescribed medications are reviewed, including dosage schedules, desired actions, and adverse reactions to be reported. Referral for home health care or physical/occupational therapy may be necessary to help the patient manage activities of daily living.

illustration

tonsillar herniation

The protrusion of the cerebellar tonsils through the foramen magnum. It causes pressure on the medulla oblongata and may be fatal.

transtentorial herniation

A herniation of the uncus and adjacent structures into the incisure of the tentorium of the brain. It is caused by increased pressure in the cranium.
Synonym: uncal herniation

uncal herniation

Transtentorial herniation.
References in periodicals archive ?
Transient ACHS due to uncal herniation is rare and management strategies for the hypoventilation are lacking.
Because there is a higher affinity for early uncal herniation and rapid neurological deterioration, any traumatic temporal lobe lesion imposes an enigma to every neurosurgeon.
We arranged DC for patients who suffered from traumatic SDH accompanied with midline shift for more than 0.5 cm or uncal herniation with brainstem compression.
The clinical presentation includes asymptomatic meningeal involvement (20), encephalopathy (21,22), cranial nerve palsies (23,24,25,26,27), neuropathy (28,29), convulsions or hemiparesis (30), obstruction of the superior sagittal sinus (31) or features of increased intracranial pressure and possibly uncal herniation (26,31).
It is recommended to maintain the catheter for three to five days due to the risk of infection (35).In patients with clinical uncal herniation or brain stem dysfunction or intracranial lesions capable of immediate surgery should be performed a craniotomy, followed by ICP monitoring (17).
Autopsy confirmed the suspected cerebellar tonsillar herniation and moderate bilateral uncal herniation. On histological examination, multiple neurons had eosinophilic cytoplasmic inclusion bodies, particularly in specimens from the hippocampi, nucleus basalis, and Purkinje cells.
Because of the sudden onset of her cerebral edema, along with the subsequent uncal herniation syndrome and her stormy postoperative course, the neuroscience ICU team decided to provide JW with a tracheostomy for long-term pulmonary protection and support.
Computed tomography of the brain indicated an intracranial hemorrhage in the left basal ganglion, with perifocal edema and uncal herniation. The patient underwent stereotactic aspiration of the hematoma in the left frontal lobe in combination with neuronavigation and drainage of the cerebrospinal fluid (CSF) by use of an external ventricular drain.
We describe a case of a patient with clinical uncal herniation elapsed by a chronic subdural hematoma.
An expanding supratentorial lesion can displace the medial temporal lobe medially and caudally, resulting in uncal herniation. The clinical picture produces the classic symptoms of herniation: Dilation of the ipsilateral pupil, hemiparesis contralateral to the side of the lesion, and coma (Hickey, 1997).
On autopsy, gross examination revealed massive cerebral edema with uncal herniation and intracytoplasmic inclusions in the brain and spinal cord.