Pathology of the Nervous System
Stacy T Black BS, R.T. (R)
Meningitis
An acute inflammation of the pia mater, arachnoid, membranes covering the brain and spinal cord.
Infecting organisms can reach meninges through…
Middle ear
Upper respiratory tract
Frontal sinus infection
Bloodstream from infection from other site.
Bacterial Meningitis – Caused by Haemophilus in children/neonates, and by meningococcus / pneumococcus in adults and adolescents.
Meningitis cont..
Viral meningitis – Caused by mumps, poliovirus, and occasionally by herpes simplex.
**Bacterial is most common form (kissing, sharing toothbrush etc.)
Radiographic Appearance
CT / MRI good at visualizing inflammation.
Plain films can demonstrate osteomylitis, paranasal sinusitis, or skull fx as underlying cause of meningitis.
Treatment
Antiviral and antibiotic medications
Encephalitis
Viral inflammation of the brain and meninges. Symptoms range from mild headache to seizures and coma.
Many viruses and a few other microbes can cause encephalitis. Herpes simplex is the most common identifiable cause of encephalitis, but often the cause cannot be found at all.
several arboviruses (meaning viruses spread by insects) cause encephalitis. Vectors such as mosquitoes can transfer the virus to humans.
Encephalitis cont..
Radiographic appearance.
A mass effect is most common and may be seen as a midline shift or as a focal mass compressing ventricles or the sylvian cisterns.
Treatment
A definite diagnosis of herpes is essential before beginning treatment because must rule out it being a abscess or tumor.
Treated with antiviral drugs.
Brain Abscess
A localized infection of the brain cased by a microorganism affecting the grey and white matter. Usually a result of infections of the middle ear, paranasal sinuses, mastoid air cells, or systemic infections.
Brain abscess cont..
Radiographic appearance
MR and CT used to image an area of abnormal density with poorly defined borders and a mass effect reflecting vascular congestion and edema.
Plain films may show evidence of underlying sinusitis, mastoiditis, or osteomyelitis.
Treatment
Antibiotics or for severe cases craniotomy.
Subdural Empyema
Infection in the space between the inner surface of the dura and the outer surface of the arachnoid.
Makes up 25% of all intracranial infections
Most common cause is the spread of infection from the frontal and ethmoid sinuses
Subdural empyema cont..
Radiographic appearance
Fluid collection adjacent to the inner border of the skull with displacement of ventricular structures.
Treatment
Medical emergency. Immediate drainage of area and sinuses.
Epidural empyema
Infection outside the dural membrane and beneath the inner table of the skull.
Invariably associated with osteomylitis
Originates from an infection in the ear or paranasal sinuses.
Epidural empyema cont..
Radiographic appearance
Poorly defined area of low density adjacent to the inner table of the skull.
Treatment
Medical emergency. Immediate drainage of area and sinuses.
Osteomyelitis
Suppurative process from the paransal sinuses, mastiod air cells, and scalp.
Infection of the cranial bones due to nuero disorder that develops 1 to 2 weeks after the onset of signs and symptoms
Osteomyelitis cont..
Radiographic appearance
Multiple radiolucent areas of the skull. Attempts at bone regeneration produce multiple areas of poorly reactive sclerosis.
Treatment
Antibiotic and or surgery.
Tumors of the CNS
Neoplasms present with seizure disorders or gradual neurological deficits like thinking slow, weakness and or headaches.
50% are primary lesions with the other half metastases
Tumors cont.
Radiographic appearance
MRI modality of choice.
Treatment
Based on location, type and extent.
Surgery, chemo and radiation therapy are all choices and can be performed with each other.
Glioma
Most common primary malignant brain tumor that consist of glial cells that have the ability to multiply.
Spread by direct extension and can cross from one cerebral hemisphere to the other.
Gliomas cont..
Types
Glioblastomas – highly malignant lesions that are predominantly cerebral.
Astrocytomas – 70% of all gliomas. Slow growing tumors that have infiltrative characteristics and can form large cavaties.
Ependymoma
Medullablastoma
olgidendrocytoma
Glioma cont..
Radiographic appearance
Most commonly seen as a single, nonhomogeneous masses that may have edema.
Treatment
Surgery or radiation therapy
Meningioma
Benign tumor that arises from the arachnoid lining and attached itself to the dura.
Seizures and neurologic defects are most often caused by mass effect.
Radiographic appearance
Anatomic distortion. A thin rim of CSF may separate the tumor from the adjacent brain.
Treatment
Surgical resection
Pituitary Adenoma
Tumors that arise form the anterior lobe and constitute more than 10% of all intracranial tumors
Nonsecreting and hormone secreting type.
Effects the ACTH and TSH hormones
Adrenocorticotropic Hormone – stimulates the adrenal cortex to secrete cortisol.
Thyroid stimulating hormone - regulates the endocrine function of the thyroid gland.
Pituitary adenoma cont…
Can cause Cushing’s disease and hyperthyroidism.
Radiographic appearance
MRI modality of choice.
Lesion associated with contralateral deviation of the pituitary stalk and an upwardly convex contour of the gland.
Treatment
Surgery ; Radiation therapy
MetastaticCarcinoma
Cancer that reaches the brain through hematogenous spread (spread through the bloodstream)
The most common neoplasms that metastasize to the brain arise in the lung and breast.
Metastatic carcinoma cont…
Radiographic appearance
Single or multiple masses situated at the junction between gray matter and white matter.
Treatment
Chemotherapy
Radiation therapy
surgery
Epidural Hematoma
Hematomas caused by acute arterial bleeding and commonly form over the parietotemporal convexity.
Cause mass effect and acute neurological symptoms
Epidural hematoma cont…
Radiographic appearance
Midline shift towards opposite side of injury.
Compression of upper mid-brain and brainstem.
Treatment
Emergency surgical decompression
Subdural Hematoma
Venous bleeding, most commonly from ruptured veins between the dura and meninges.
Because of the low pressure tend to have a chronic gradual course with symptoms of headaches, agitation and other neurologic problems, it is hard to diagnose early without radiology exam.
Subdural hematoma cont...
Radiographic appearance
Zone of increased density that follows the surface of the brain and has a crescent shape adjacent to the inner table of the skull.
Treatment
Small subdural hematomas will resorb.
Severe ones require surgical evacuation of the hematoma
Drug therapy
Intraventricular catheter.
Cerebral Contusion
Injury to the brain tissue caused by movement of the brain within the calvaria after blunt trauma to the skull.
Contusions happen when the brain strikes the rough surfaces of the skull such as the orbital roof and petrous ridges
Cerebral contusion con…
Frontal and anterior temporal regions are the most common sites of injury.
Radiographic appearance
Low-density areas of edema and tissue necrosis
Treatment
Hospitalization
Medications
Intracerebral Hematoma
Traumatic hemorrhage into the brain parenchyma from shearing forces.
Injury to the intima of intracranial vessels can cause the development of traumatic aneurysms.
Intracerebral hematoma cont…
Radiographic appearance
Well-circumscribed, homogeneous, high density region that is usually surrounded by areas of low density edema.
Treatment
Evacuation of acute subdural hematomas.
Surgery if aneurysms
Subarachnoid hemorrhage
Injury to surface veins, cerebral parenchyma, or cortical arteries can produce bleeding into the ventricular system (blood on CSF)
Radiographic appearance
Increased density within the basilar cisterns, cerebral fissures, and sulci.
Treatment
Surgical evacuation and vessel repair if bleeding continues.
Less invasive methods are drug therapy and catheter placement.
Stroke
Neurological deficit due to lack of circulation to the brain.
CVA (cerebral vascular accident) - blood supply to a part of the brain is suddenly interrupted
Ischemic stroke – Complete occlusion
hemorrhage
TIA (Transient Ischemic attack) is a disturbance in brain function that lasts less than 1 hour and results from a temporary blockage of the brain's blood supply
Stroke cont…
Radiographic appearance
The purpose of a radiographic evaluation in the acute stroke patient is not to confirm the diagnosis of the stroke but rather exclude other processes that can simulate the clinical finding.
Initial appearance is a triangular or wedge shaped area of hypodensity.
Eventually produces a mass effect.
Brian tissue atrophies
Stroke cont…
Treatment
All stroke patients are placed on bed rest with reduced external stimuli to lower cerebral oxygen demands.
Medications to lower intracranial pressure
Anticoagulants (Heparin, Warfarin)
Multiple Sclerosis
A chronic progressive disorder that causes demyeliniation of the CNS.
Primarily involves the spinal cord, optic nerve, and central white matter of the brain.
Impairment of nerve conduction caused by degeneration of myelin sheaths.
Multiple Sclerosis cont…
Radiographic appearance
Scattered plaques of demyeliniation .
Treatment
Immunosuppressive agents may help limit the autoimmune attack.
Antiviral drugs may slow down the progress of the disease.
Can only aid in slowing progress. There is no cure.
Alzheimer’sDisease
Condition that causes cerebral atrophy, causing the patient to be confused, disorientated, and forgetful.
Alzhemiers cont…
Radiographic appearance
Cerebral atrophy, including symmetrical enlarged ventricles with prominence of the cortical sulci.
Treatment
Diet, education, memory aids may help slow the dementia but there is no cure.