teaching file

Cervical Myelopathy

Cervical myelopathy is a condition describing a compression of the spinal cord at the cervical level of the spinal column resulting in spasticity , hyperreflexia, pathologic reflexes, digit/hand clumsiness, and/or gait disturbance. Classically it has an insidious onset progressing in a stepwise manner with functional decline.

An MRI can provide some guidance for clinicians and patients about the potential for improvement. Based on a systematic review of MRI findings by Tetreault et al. in 2013:

  • High-intensity changes on T2 and low intensity on T1: poorer recovery rate, worse motor symptom improvements
  • More frequent high signal intensity on T2 predicts worse recovery.

MRI: Canal space of less than 10 mm indicates stenosis. Best to evaluate cord and disk space. Of note, up to 19% of asymptomatic patients have major cervical abnormalities which can be misleading. An MRI is imperative to evaluate spine pathologies. Compression and signal changes on T1 and T2 are indicative of myelopathy pathologies.

Cervical spondylotic myelopathy will frequently involve compression of the lateral corticospinal tracts resulting in voluntary skeletal muscle control, and the spinocerebellar tracts proprioception. Together, these deficits are responsible for the wide-based spastic gait with clumsy upper extremity function that is classic to cervical myelopathy. Additional commonly involved spinal cord regions are the spinothalamic tracts, which are responsible for contralateral pain and temperature sensation, the posterior columns, which are responsible for the ipsilateral position and vibration sense, and the dorsal nerve root, which is responsible for dermatomal sensation

Reference:

 10.1177/2192568217701714

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Persistent Metopic Suture.

The persistence of the metopic suture is called metopism. This suture disappears by the second or third year of life. It is thought to be a normal variant of the cranial sutures . It forms from the lack of union of the two frontal bones during embryonic development.

Metopism is found in approximately 5% of Asians and 9% of European Caucasians and 1% of Blacks.

Reference:

Castillo SMA, Oda YJ, Santana GDM. “Metopism in Adult Skulls from Southern Brazil”. International Journal of Morphology. 2006; 24: 61-66.

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Epidermoid Cyst in the Cerebellopontine Angle

Epidermoid tumors arise from ectoderm trapped within/displaced into the central nervous system. They show predilection for CPA Angle (up to 40%), 4th ventricle, suprasellar region, and spinal cord. They are the 3rd most common CPA tumor, comprising approximately 7% of CPA pathology. CPA lesions can produce 5th and 7–12th cranial nerve neuropathies. 

Recurrent episodes of aseptic meningitis caused by cyst content rupture may occur. Symptoms include fever, meningeal irritation, and hydrocephalus. A 26-year-old female presented with headaches. Head magnetic resonance imaging (MRI) revealed right CPA tumor with brain stem compression. There was evidence of restricted diffusion in diffusion-weighted imaging, typical of epidermoid tumor.

The tumor grows slowly and is soft and very pliable, conforming to the shape of the adjacent brain and CSF spaces in which it is growing. The cysts, frequently referred to as “pearly tumors” because of their gross external appearance, account for approximately 0.2% to 1.8% of brain tumors. Although
congenital in nature, they usually do not present clinically until the third or fourth decade. The cysts may be extradural or intradural in location. The intradural lesions are frequently located in the cisterns of the cerebellopontine angle, supra- and parasellar regions, and middle cranial fossa, as well
as the cisterna magna. Tumors may also develop in the tela choroidea, usually in the temporal horn of the lateral ventricle but occasionally in the fourth ventricle.

On CT the lesions are hypodense and do not enhance with contrast material. They are difficult to differentiate from arachnoid cysts based on their density; however, their external surface is usually lobulated in configuration compared with the smooth surface of an arachnoid cyst. There may occasionally be focal calcifications in their walls. In contrast to arachnoid cysts, epidermoids tend to engulf and surround vessels and cranial nerves, whereas arachnoid cysts displace such structures.

On T1-weighted MR images, epidermoid tumors demonstrate subtle hypointensity compared to CSF. There is usually mild inhomogeneity of low intensity, with some patchy regions of isointensity within the lesion. On T2-weighted sequences the tumors show marked hyperintensity similar to or greater than that of CSF, with significant heterogeneity of the signal.

The low-intensity signals within the tumor hyperintense pattern are probably the result of the cellular
debris and solid cholesterol crystals within the cysts . A high-intensity rim may surround the portion of the cyst on T2-weighted sequences that probably represents a CSF cleft. The tumors may be dumbbell shaped in configuration and extend from the middle cranial fossa into the posterior fossa. They may have a smooth external surface but in most instances demonstrate a lobulated appearance. No free fatty
acids have been found in epidermoid cysts that are of low intensity on the T1-weighted sequences. On MRI, epidermoids are distinctly different from arachnoid cysts, in that epidermoid tumors are virtually never isointense to CSF on MR images when using FLAIR. In addition, diffusion- weighted imaging demonstrates reduced diffusion within epidermoids, simplifying the diagnosis and aiding visualization.

Reference:

Atlas S. Chapter 11: Adult Brain Tumors p581

JM

Fibrous Dysplasia-Nasal Cavity

Fibrous dysplasia is a fibro-osseous medullary lesion; it affects a single bone (monostotic) in 70% of cases and more than one bone (polyostotic) in 30% of cases. Polyostotic fibrous dysplasia manifests in association with skin hyperpigmentation and endocrine abnormalities in McCune-Albright syndrome. Fibrous dysplasia in the craniofacial bones accounts for 35% of monostotic fibrous dysplasias, even if it involves several adjacent bones. The skull base and facial bones are common sites of involvement, and in this setting, they may encroach on the nasal cavity. The jaws are the most frequently affected bones. Fibrous dysplasia is more common in the 1st and 2nd decades of life and has a slight female predilection.

The clinical manifestations of fibrous dysplasia include painless swelling, facial deformity, exophthalmos, and symptoms related to narrowing of skull base foramina. Fibrous dysplasias that undergo periods of increased activity can cause increased swelling and discomfort and may mimic osteomyelitis on bone scans. The growth of this lesion tends to decrease after puberty. The diagnosis is confirmed by the presence of the mutation of GNAS 1α, which enables the differentiation of fibrous dysplasia from other fibro-osseous lesions.

The imaging characteristics of fibrous dysplasias depend on the stage of development of the disease and the amount of bone matrix, and vary from lucent to sclerotic lesions. At plain radiography and CT, this lesion has the characteristic ground-glass appearance, which is secondary to the amount of woven bone present. Fibrous dysplasia manifests as an expansile lesion that has ill-defined margins and a thinned cortex; it replaces normal bone but rarely involves bone erosion. CT is key to rendering an accurate diagnosis, given that fibrous dysplasias can exhibit aggressive characteristics at MR imaging, mimicking malignant lesions.

At MR imaging, the appearance of fibrous dysplasia is variable, but it typically has low signal intensity on T1-weighted images. The signal intensity is variable on T2-weighted MR images: it can be low, intermediate, or high. At contrast-enhanced imaging, there is internal heterogeneous enhancement, with the fibrous component typically enhancing more than the osseous component. As a benign lesion, fibrous dysplasia has increased diffusivity on apparent diffusion coefficient maps, which can help in differentiating it from a malignant lesion.

Reference:

https://doi.org/10.1148/rg.2017170064

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Optic Neuropathy in Patients with Fibrous Dysplasia

Fibrous dysplasia (FD) is a rare, mosaic disorder in which normal bone and marrow are replaced with fibro-osseous tissue. Expansile lesions lead to deformities, fractures, and disability. FD may involve one or multiple bones, and may occur in association with skin macules and hyperfunctioning endocrinopathies, termed McCune-Albright syndrome (MAS)

Vision loss due to optic neuropathy (ON) is a severely disabling complication of FD. ON is a nonspecific diagnosis referring to damage and atrophy of the optic nerve due to any cause.

There is evidence suggests the mechanism of ON in FD is more complex and likely multifactorial. Since growth hormone excess is an established risk factor for ON in FD/MAS, optic nerve elongation, in the setting of acromegalic macrocephaly, is another proposed mechanism. Furthermore, FD involvement of the facial skeleton leading to asymmetry and proptosis may also stretch the optic nerve leading to ON. Because of this heterogeneity, management of ON in FD is challenging and has been the subject of controversy for decades.

Reference:

https://doi.org/10.1002/jbmr.4129

JM

Second branchial cleft Cyst.

The branchial arches represent the embryological precursors of the face, neck and pharynx. Anomalies of the branchial arches are the second most common congenital lesions of the head and neck in children. They may present as cysts, sinus tracts, fistulae or cartilaginous remnants and present with typical clinical and radiological patterns dependent on which arch is involved.

different cases

Second branchial cleft anomalies most commonly present as cysts followed by sinuses and fistulae. Most are present within the submandibular space but they can occur anywhere along the course of the second branchial arch tract which extends from the skin overlying the supraclavicular fossa, between the internal and external carotid arteries, to enter the pharynx at the level of the tonsillar fossa. They have previously been classified into four different subtypes by Bailey in 1929:

  • Type I – Most superficial and lies along the anterior surface of sternocleidomastoid deep to the platysma, but not in contact with the carotid sheath.
  • Type II – Most common type where the branchial cleft cyst lies anterior to the sternocleidomastoid muscle, posterior to the submandibular gland, adjacent and lateral to the carotid sheath.
  • Type III – Extends medially between the bifurcation of the internal and external carotid arteries, lateral to the pharyngeal wall.
  • Type IV- Lies deep to the carotid sheath within the pharyngeal mucosal space and opens into the pharynx.
Case 1-Infected

In adult patients, the main diagnostic consideration is whether the cystic lesion represents a metastatic lymph node and subsequent imaging is directed at identifying a primary neoplastic lesion. This is particularly true if there is no history of chronic neck fullness and no history of a recurrent mass following upper respiratory tract infections. Occult papillary thyroid cancer is also a recognised cause of cystic metastases and may also seen seen in children. Fluid aspiration in association with thyroglobulin levels may aid the distinction.

case 2 infected-treatment.

On ultrasound, second branchial cleft cysts are typically well-circumscribed, thin-walled and anechoic with evidence of compressibility and posterior acoustic enhancement. They may contain internal echoes compatible with internal debris.

Case 3

On CT imaging, they are well-circumscribed, low-density cystic masses with a thin wall. If they become infected, this may become thick-walled with evidence of mural enhancement, localised inflammatory change and perilesional fat stranding. The mural thickening is attributed to the response of lymphoid tissue.

case 4

MRI is better suited in the assessment of deep tissue involvement. On T1-weighted imaging, they may turn from low to high signal depending on the proteinaceous content of the cyst, but are typically hyperintense on T2. As with CT imaging, mural thickening and enhancement varies with inflammatory change and typically occurs in the setting of infection. A tissue ‘beak’ between the internal and external carotid arteries is pathognomonic of Bailey type III cysts. Surgical management involves complete surgical excision encompassing the external sinus opening with dissection of the sinus tract.

case 5

Reference:

Adams, A., Mankad, K., Offiah, C. et al. Branchial cleft anomalies: a pictorial review of embryological development and spectrum of imaging findings. Insights Imaging 7, 69–76 (2016). https://doi.org/10.1007/s13244-015-0454-5

https://doi.org/10.1007/s13244-015-0454-5

JM

How to measure The callosal angle. Atrophy vs Hakim-Adams.

The callosal angle has been described as useful in discriminating iNPH-Hakim–Adams Syndrome from ventricular dilation secondary to atrophy. the angle should be measured on a coronal image perpendicular to the anterior commissure – posterior commissure (AC-PC) plane at the level of the posterior commissure.

A normal value is typically between 100-120°. In patients with iNPH that value is lower, between 50-80°

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Lumbar Synovial Cysts

SCs are herniations of the synovial membrane through the capsule of a joint filled by synovial fluid, which may or may not keep a communication with the joint.

The MRI features consists of rounded cystic lesions arising from the medial aspect of degenerated facet joints filled with synovial fluid, usually smaller than 20 mm. They tend to course with lateral recess stenosis and present dense adhesions to dura and nerve roots.

The great majority of SCs arising from facet joints occur in the lumbar spine, L4/L5 being the most affected level. These lesions are seldom reported in the cervical spine and are even rarer in the thoracic spine.

They are thought to serve as drainage reservoirs for the excessive joint effusion in the setting of any arthropathy, escaping from its regular location through a one-way-valve mechanism into the area of least resistance.

Reference:

10.1007/s13244-016-0463-z 

JM

Intrathoracic Goiter

Thyroid goiters are estimated to occur in approximately 5% of the population worldwide . Most are in the neck, yet between 3% and 17% of these goiters extend into the thorax and are also called substernal, particularly when more than 50% of the mass is below the suprasternal notch . Intrathoracic goiters are
usually in the anterior mediastinum. A small subset of 10-25% may be found in the posterior mediastinum Radiologic imaging is an important step in the workup of these patients because the surgical approach depends on the location and size of the intrathoracic goiter.

Anterior Versus Posterior: Most intrathoracic goiters lie anterior to the recurrent laryngeal nerve and anterolateral to the trachea. Goiters in the anterior mediastinum arise secondarily from the isthmus or the lower aspects of the thyroid lobes. As the mass grows inferiorly, the great vessels may be displaced laterally, framing the mass on chest radiography Posterior mediastinal goiters arise as secondary goiters from the posterolateral aspects of the thyroid gland and descend posterior to the great vessels. Most are right- sided because of anatomic barriers formed by the aortic arch and its branch vessels. Even goiters that originate from the left lobe are deflected to the right by the left innominate vein and left common carotid and subclavian arteries. The esophagus may be markedly displaced to the contralateral side and the trachea may be pushed anteriorly.

The goiter descends inferiorly along the fascial planes of the neck, following a path of least resistance into the superior mediastinum

case 2

Although most patients are asymptomatic, stridor due to tracheal compression is the most common symptom . Findings include a sharply marginated mediastinal mass with punctate calcifications.

The differential diagnosis includes calcified lymph nodes. treated lymphoma. and a hemorrhagic primary mediastinal mass.

Reference:

AJR 1999;173:471-475 0361-803X/99/1732-471

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Myxopapillary Ependymoma CSF dissemination.

Myxopapillary ependymomas are highly vascular neoplasms characterized by abundant supporting fibrous connective tissue stroma, mucinous degeneration of this supporting stroma, and mucin secretion by the tumor cells.

Multiple tumors have been reported in 1 4%-43% of patients and may be due to dissemination of tumor in the spinal subarachnoid space. Certain sacral and presacral lesions behave aggressively and
metastasize to the lymph nodes, lung, and bone . On the other hand, recurrence is rare following complete excision of well-circumscribed lesions.

Ependymomas of the brain frequently calcify, calcification is extremely unusual in spinal ependymoma.

Bulky, obstructive lesions are associated with a high protein content of the CSF that may obscure differentiation of the tumor from the CSF. The signal intensity of the CSF can also be affected by subarachnoid hemorrhage. Almost all ependymomas enhance intensely after administration of
contrast material. Contrast-enhanced imaging is useful in differentiating the tumor from the spinal cord, defining intratumoral cysts, and identifying intradural metastases.

Reference:

https://doi.org/10.1148/radiographics.18.3.9599402

JM