Cortical venous thrombosis

Findings

Figure 1: Noncontrast CT demonstrates a right frontoparietal cortical hemorrhage with surrounding edema.
Figure 2: Axial FLAIR image demonstrates no underlying mass lesion. Surrounding edema is present.
Figure 3: Axial gradient echo image demonstrates low signal in the area of previously noted hemorrhage consistent with blood products.
Figure 4: Contrast enhanced T1 axial weighted image reveals vague contrast enhancement in the region of hemorrhage with no identifiable mass lesion.
Figure 5: MRA of the Circle of Willis demonstrates no aneurysm or vascular malformation.
Figure 6: Catheter angiography in the venous phase displays abrupt cut-off of a deep cortical vein consistent with a deep cortical vein thrombosis.


Diagnosis: Cortical venous thrombosis


Cerebral venous thrombosis is a relatively uncommon disorder with 2-7 cases per million individuals in the general population. Over 100 causes of venous thrombosis have been identified which are broken down into two groups: (1) systemic/clinical conditions that promote thrombosis and (2) local processes that alter venous flow. Commonly encountered systemic causes include factor V leiden, protein C and S deficiencies, peripartum state, oral contraceptive use, and malignancy. No cause of venous thrombosis is identified in 25% of cases.

Cerebral venous thrombosis is difficult to diagnosis because it presents with a wide variety of clinical manifestations which also depend on the severity and location of the thrombosis. Most patients experience generalized neurologic symptoms including headache (75-95% of cases), blurred vision, altered consciousness, nausea and vomiting. Focal neurological defects including seizures may occur and are more common in individuals with parenchymal changes. In addition, the clinical manifestations may wax and wane, likely secondary to repeated episodes of thrombosis and recanalization.

The pathophysiology of cerebral venous thrombosis is related to rising venous pressure due to obstruction of venous drainage. Infarction results in 50% of cases and may cause vasogenic edema and hemorrhage. Isolated cortical venous thrombosis is rare, with fewer than 20 cases in the literature. Most patients with this disorder have underlying coagulation disorders or chronic inflammatory conditions. The most common imaging pattern, as in this case, is focal cortical edema and/or hemorrhage which is nonspecific and includes a broad differential diagnosis.

The primary therapy for cerebral venous thrombosis is anticoagulation. Anticoagulation halts clot propagation and aids in dissolution via the fibrinolytic system. Poor outcomes are associated cortical hemorrhage, thrombosis of the deep venous system and central nervous system infection. These patients may be candidates for more aggressive therapy with local thombolysis.

Atlanto-occipital dislocation

Findings

The scout view of the head CT shows marked prevertebral soft tissue swelling. There is also subjective increased interspinous distance between C1 and C2. The cervical spine CT coronal view demonstrates irregularity of the occipital condyle joint spaces with the lateral masses of C1. The cervical spine CT sagittal view demonstrates separation of the basion from the odontoid process, measuring approximately 15mm. The cervical spine MRI demonstrates significant abnormal signal in the paraspinous soft tissues. It also demonstrates increased basion - odontoid space.

Differential diagnosis:
- Atlanto-occipital dislocation
- Ligamentous injury
- Cervical spine fracture(s)
- Artifact due to patient rotation


Diagnosis: Atlanto-occipital dislocation


Key points

Atlanto-occipital dislocation is a true neurological emergency, often associated with direct spinal cord injury, quadriplegia, respiratory arrest, and death.
Injury results from rapid deceleration with either hyper flexion or hyperextension.
Vascular injuries are common, ranging from carotid and vertebral artery dissection to complete transection.
Patient survival depends on immediate on-scene resuscitation, spinal immobilization, rapid transportation, rapid diagnosis, and a high index of suspicion.
Occurs more often in children, partly due to larger relative head size, and ligamentous laxity.
Non-traumatic causes include Down's syndrome and rheumatoid arthritis.
Lateral X-Ray findings can include prevertebral soft tissue swelling (usually marked), increased basion-dens interval (more than 12mm).
If plain films are inconclusive, cervical spine CT findings can include prevertebral soft tissue swelling, occipital condyle fracture, irregularity of the articulation between the occipital condyles and the lateral masses of C1.
Cervical spine MRI findings can include abnormal fluid signal in the region of the interspinous ligament or nuchal ligament.

Sickle cell disease with Moyamoya picture

Findings

Figure 1: Axial T1 weighted images demonstrates expansion of the diploic space consistent with extramedullary hematopoesis, a finding identified in hemoglobinopathies such as sickle cell disease and thalassemia.
Figure 2: FLAIR images demonstrate areas of increased signal in the left frontal white matter indicating ischemic changes.
Figure 3: Gradient echo image demonstrates increased susceptibility in the left centrum semiovale indicating hemosiderin deposition resulting from prior hemorrhage.
Figure 4, Figure 5, Figure 6: Diffusion weighted images demonstrate scattered areas of restricted diffusion, indicating acute infarcts in a watershed distribution in the left internal carotid artery territory.
Figure 7: MR angiography demonstrates absence of the anterior cerebral arteries with narrowing of the distal left internal carotid artery accounting for the acute scattered infarcts in the left internal carotid territory.


Diagnosis: Sickle cell disease with Moyamoya picture


Sickle cell disease is a hemoglobinopathy where abnormal strands of hemoglobin (Hgb S) stiffen when deoxygenated. This results is deforming of erythrocytes which produce microvascular occlusion and hence, ischemic changes. Because of abnormal adherence of sickled erythrocytes, they deform the internal elastic lamina and muscularis resulting in vasculopathy. By ten years of age, 44% of sickle cell patients demonstrate cerebral ischemia, infarction and atrophy (35% of these lesions are silent).

Cortical involvement in sickle cell disease demonstrates a variety of findings. Findings include evidence of acute or chronic infarcts in the cortical or deep white matter on T2 and FLAIR weighted images, particularly in a watershed distribution.

Typical findings on MR include hemorrhagic infarcts, punctate flow voids in the basal ganglia and an abnormal marrow signal with an expanded diploic space. Aneurysms in atypical locations, lack of vascular flow voids with prominent leptomeningeal and external carotid collaterals and stenosis of the distal internal carotid and proximal circle of Willis are typical vascular findings of sickle cell disease.

Differential diagnosis for the cerebrovascular findings of sickle cell disease include vasculitis of autoimmune and infectious etiologies. Substance abuse, particularly crack-cocaine, and radiation vasculitis can also produce similar findings. Connective tissue disorders such as Marfan and Ehlers-Danlos syndrome as well as homocystinuria can produce progressive arterial narrowing and occlusion. Thalassemia, another hemoglobinopathy, does not produce vascular findings but will result with a thickened skull with an expanded diploic space.

Post-varicella basal ganglia infarct

Additional clinical history: Patient has a history of varicella infection.


Findings

Focal area of hyper intense signal R basal ganglia with increased signal on diffusion imaging and decreased signal on ADC map. Post contrast images showed no enhancement.

Differential diagnosis
- Basal ganglia infarct
- Basal ganglia neoplasm (germinoma)
- Infection (parainfluenza)


Diagnosis: Post-varicella basal ganglia infarct


Key points

Generally presents with unilateral hemiparesis.
Neurologic deficits improve over time with good prognosis.
Usually occurs between 1-4 months after varicella infection.
Etiology is spasm of lenticulostriate arteries.
Treatment: No consensus but steroids or antiplatelet agents are being used.

Warthin tumor

Findings

Figure 1, Figure 2, Figure 3, and Figure 4: CT images of the bilateral parotid Warthin tumors.


Diagnosis: Warthin tumor


Warthin tumor (also referred to as papillary cystadenoma lymphomatosum) is the second most common benign tumor of the parotid gland with only pleomorphic adenoma being more common. Warthin tumor comprises 4%-10% of all parotid tumors. They are the most common bilateral salivary gland tumor with an estimated 5% to 14% of cases presenting with bilateral glandular involvement.

Warthin tumors are ovoid, encapsulated tumors that are either completely solid or solid with cystic components. The most common location of presentation is the parotid tissue adjacent to the angle of the mandible. Warthin tumors are believed to arise from the embryologic entrapment of heterotopic salivary gland ductal epithelial tissue within intraparotid or periparotid lymph nodes.

Patients typically present with painless swelling. The peak incidence is the fifth to seventh decade of life. Risk factors include cigarette smoking and radiation exposure. Malignant degeneration and facial nerve involvement are extremely rare. Treatment for Warthin tumors is surgical with superficial parotidectomy.


Imaging

Ultrasound images demonstrate a well demarcated, hypoechoic mass or a solid mass with multiple anechoic internal areas. On CT, Warthin tumors are homogeneous, enhancing soft tissue densities that contain no calcification. If calcifications are present in a benign appearing parotid mass, the diagnosis of pleomorphic adenoma should be favored. Warthin tumors are traditionally located in the posterior aspect of the tail of the parotid gland but the tumors have been known to arise from periparotid lymph nodes. Cyst formation is common and the larger the tumor the greater the chance for cystic change. On MR imaging, the tumors have low T1 and high T2 signal (similar to pleomorphic adenomas). Warthin tumors are rich in mitochondrium and therefore will accumulate Tc-99m pertechnetate on salivary scintigraphy. Unfortunately, oncocytomas and the extremely rare oncocytic carcinoma both accumulate pertechnetate as well. Imaging findings that suggest a malignant parotid mass include; irregular margins, heterogeneous density/signal intensity, regional lymphadenopathy, adjacent soft tissue or bone invasion, and facial nerve perineural spread of tumor. Often, parotid masses will go to biopsy for a definitive diagnosis.

Spinal muscular atrophy type I: Werdnig-Hoffmann disease

Findings

Figure 1, Figure 2, Figure 3: There is diffuse cerebral edema with loss of grey-white interface. A "hyperdense" cerebellum and hyperdense MCA vessels are seen. These are, in fact, normal in attenuation, but appear bright when compared with the hypoattenuated adjacent edematous brain.
Figure 4, Figure 5, and Figure 6: MR images demonstrate periventricular cystic spaces and are evidence of remote ischemic changes. There is a subdural fluid collection.


Diagnosis: Spinal muscular atrophy type I: Werdnig-Hoffmann disease


Spinal muscular atrophy (SMA) collectively refers to a family of disorders characterized by progressive degeneration of motor neurons in the spinal cord and brainstem. These disorders are inherited in an autosomal recessive pattern, with deletions or mutations in the survival motor neuron (SMN) gene at the 5q11 locus. Patients present with diffuse symmetric proximal muscle weakness, which is more pronounced in the lower extremities.

In general, there are three recognized types of SMA. These three types are clinically distinguished from one another based upon the age at presentation and the severity of disability. An earlier onset of disease correlates with a worse prognosis, however prognosis is primarily attributed to the severity of muscle weakness.


SMA Type: 1 = Werdnig-Hoffmann Disease

Age at presentation: Preterm – 6 mo
Clinical presentation: Hypotonia, unable to sit without support
Prognosis: Few survive 1 year; death by age 2


SMA Type: 2 = Intermediate type

Age at presentation: 6 mo – 15 mo
Clinical presentation: Proximal weakness; able to sit; unable to stand or walk unaided
Prognosis: Death due to respiratory complications, usually > 2 yo


SMA Type: 3 = Kugelberg-Welander Disease

Age at presentation: 12 mo – adolescence
Clinical presentation: Delayed motor development; able to stand and walk
Prognosis: Death in adulthood


Werdnig-Hoffman disease is both the most severe and the most common form of SMA. Mothers may report decreased fetal movement during the last trimester of pregnancy, and neonates typically present with generalized hypotonia. Involvement of the bulbar muscles leads to difficulty feeding, aspiration, and pneumonia. Involvement of the diaphragm and intercostal muscles leads to progressive respiratory insufficiency. All of these factors result in chronic hypoxia, and eventually death.

The diagnosis of SMA in patients presenting with the appropriate clinical signs and symptoms is confirmed with electromyography, nerve conduction studies, muscle biopsy, and molecular (genetic) analysis. Treatment is primarily supportive.

Hypoxic-ischemic injury to the brain in the term infant is dependent on two factors: the length of the hypoxic episode and the degree of the hypoxia. The damage caused as a result of partial hypoxia differs from that of profound asphyxia.

Chronic respiratory insufficiency in the term neonate will cause neuronal cell death, leading to generalized cerebral cortical atrophy and edema. Central structures (basal ganglia, thalami), and posterior fossa structures, are typically spared.

Total anoxia will lead to hypoxic-ischemic encephalopathy (HIE). In this case, the regions of the brain most affected are those with the highest metabolic demand. This includes the basal ganglia, thalami, hippocampi, brainstem, corticospinal tracts, and sensorimotor cortex.

In an infant with Werdnig-Hoffmann disease, CT scan will reveal:
- Decreased brain tissue attenuation
- Prominent sulci, intrahemispheric fissure, and dilated anterior subarachnoid space

MR is the most sensitive and specific imaging modality in the identification of neonatal hypoxic-ischemic injury. T2-weighted images of the spinal cord in Werdnig-Hoffmann disease will reveal high-signal intensity lesions in the region of the anterior horn secondary to motor neuron loss and associated edema.

Labyrinthine ossificans

Findings

Increased hazy densities bilaterally in the membranous component of the cochlea. The left tympanic membrane demonstrates focal thickening in the pars flaccidum. There is mild soft tissue density within the left external auditory canal. (Prior L left myringotomy tube).

Differential diagnosis:
- Labyrinthine ossificans
- Cochlear otosclerosis
- Cochlear aplasia
- Labyrinthine schwannoma
- Intravestibular lipoma


Diagnosis: Labyrinthine ossificans


Discussion

Labyrinthine Ossificans (LO) refers to ossification occurring within the luminal spaces of the labyrinth and cochlea. This typically is secondary to a destructive or inflammatory process and represents a healing response. Specific processes may be infectious, traumatic or surgical in nature. LO is most commonly seen after bacterial meningitis in children. Not surprisingly, LO secondary to bacterial meningitis represents the most common cause of acquired childhood deafness.

The typical clinical presentation is a child between 2-18 months of age with a history of recent meningitis presenting with bilateral sensorineural hearing loss. Although not a common presenting symptom, patients may also present with vertigo. Meningitis in the age group of interest is usually secondary to either streptococcus pneuomoniae or hemophilus influenzae.

Other presentations may include ear infection, bout of viral illness, or severe head trauma.

Ceftazidime is the antibiotic of choice to prevent otogenic and meningogenic labyrinthitis. This is secondary to the high antibiotic concentrations levels that can be reached in the CSF and endolymph. Steroids have shown some promise and are felt to decrease the rate of hearing loss. This is likely secondary to decreased inflammatory response, granulation tissue formation and collagen formation. Cochlear implantation may be an option if the cochlear nerve is still preserved. In cases of severe vertigo, labyrinthectomy may be warranted.


Radiologic overview

High resolution, 1 mm thick coronal and sagittal CT images are recommended. Post contrast images are not needed. The best clue on CT imaging is bone deposition within the membranous labyrinth. Findings vary based on the severity of the disease. Mild cases of LO may simply demonstrate increase haziness of the luminal spaces of the membranous labyrinth. Moderate cases may demonstrate areas of interspersed bone invading the luminal spaces. Severe cases may show complete destruction of the membranous labyrinth with extensive bony replacement of the luminal spaces.

Although CT imaging is used more often, MRI can be also assist in diagnosis. MRI offers the advantage of visualizing fibrous destruction of the membranous labyrinth which may be difficult to appreciate on CT. T2 weighted images are most useful in helping make the diagnosis. In mild LO, there is partial replacement of the hyperintense signal normally seen in the fluid spaces of the membranous labyrinth. In cases of moderate LO, hypointense focal areas are noted corresponding to bony replacement of the fluid spaces. Finally, complete absence of the T2 hyperintensity correlates with complete bony replacement of the fluid spaces seen in severe LO. As with CT, thin cuts on MR imaging are recommended.