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MASS LESION

Tue, 01/01/2008 - 13:53 — oxygen

PATIENTS WITH A MASS LESION

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POSTERIOR FOSSA LESION

brain1_0.jpg

Intracranial mass lesions include:
-congenital
-neoplastic (benign, malignant)
-infectious (abscess, cyst)
-vascular (hematoma, AVM)

Common primary tumors include:
-glial cells astrocytoma, oligodendroglioma, glioblastoma
-ependymal cells ependymoma
-support tissues meningioma, schwanoma, choroidal papilloma

Intracranial mass lesions genrally present according to:
-growth rate:
-location:
-ICP

Growth rate
rapid growth rate: acute presentation (ex. headache, nausea, vomiting, papilledema, inc ICP)
slow growth rate: slow progressive presentation ex. weakness leading to focal neurological deficit

Location
supratentorial: associated with: seizures, hemiplegia, aphasia,
infratentorial: associated with: cerebellar dysfunctino (ex.ataxia, nystagmus, dysarthria)
brain stem: associated with: cranial nerve palsies, ΔMS, respiratory abnormalities

ICP
Increased ICP associated with: headache, nausea, vomiting, papilledema, focal neurological deficit, ΔMS

POSTERIOR FOSSA LESION

OBSTRUCTIVE HYDROCEPHALUS
-obstruction of the 4th ventricle or cerebral aqueduct by infratentorial masses which may obstruct CSF outflow
-resultant increase in ICP
-reduction of ICP is often performed by ventriculostomy prior to induction of general anesthesia

BRAINSTEM INJURY
-vital circulatory and respiratory centers within the brainstem are vulnerable to injury during operations in the posterior fossa
-injuries to the brain stem may occur due to:

Direct surgical Trauma

retraction ischemia
Respiratory center injury often is associated with circulatory changes which involve:
-blood pressure
-heart rate
-rhythm
*neurosurgeon should be informed of circulatory changes suggestive of respiratory center injury

Monitoring
-evoked potential helps assess neural integrity during the surgical protection
ex. BAEP: allows for monitoring CN VIII during resection of acoustic neuromas
-EMG: allows for the monitoring of CN VII
Postioning of patients with posterior fossa surgery may be:
-modified lateral position
-prone position
-sitting position

*head should always be elevated above the level of the heart

Sitting position involved with increase chance of :
-pneumocephalus
-venous air embolus (VAE)

Comments

Fri, 09/18/2009 - 06:35 — nomzz

Intracranial Mass

Intracranial Mass Lesions:Papilledema with intracranial lesion (medulloblastoma).Signs and symptoms: The symptom most often associated with intracranial mass lesions is headache, although it has little localizing value. The typical headache from mass lesion has a boring pain, and may awaken the patient during sleep. Projectile vomiting without nausea is a common feature. More commonly, the headache is dull, moderate in intensity and chronic. Often, coughing, bending over and exertion will exacerbate the headache.
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Other signs associated with intracranial mass lesions include transiently obscured vision, seizures, loss of consciousness, changes in mental status and drop attacks. In the hydrocephalic state--which may occur when the mass blocks cerebrospinal fluid flow and expands the cerebral ventricles--there may be loss of memory, gait ataxia, balance disturbance and urinary incontinence.
The clinical finding most associated with an intracranial mass lesion is papilledema. Other findings may include horizontal diplopia from unilateral or bilateral CN VI palsy.
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