POSTER SECTIONS Coverpage Learning objectives Background Findings and procedure details Conclusion Personal information and conflict of interest References

ECR 2020 / C-12515

A Twist in the ‘Tail’ – Lesions found on the last axial slice in brain imaging

Congress:

ECR 2020

Poster Number:

C-12515

Type:

Educational Exhibit

Keywords:

Neuro, Anatomy, CNS, Head and neck, CT, MR, Education, Education and training, Not applicable, Performed at one institution

Authors:

V. B. Pai¹, Y. Y. Sitoh², B. S. Purohit¹; ¹Singapore /SG, ²SINGAPORE/SG

DOI:

10.26044/ecr2020/C-12515

DOI-Link:

https://dx.doi.org/10.26044/ecr2020/C-12515

Fig. 1: Patient presents with sudden onset of right hemiparesis

Fig. 2: A focus of restricted diffusion (solid arrows in Fig. A, B) in the medial...

Fig. 3: Left sided weakness.

Fig. 4: Axial CT image (Fig. A) of the brain reveals a hyperdense lesion in the medulla...

Fig. 5: History headache since 1 year.

Fig. 6: Axial CT image (Fig. A) reveals fullness at the foramen magnum (solid arrow),...

Fig. 7: Long standing generalized weakness

Fig. 8: Axial T2 image (Fig. A) reveals an intermediate signal intensity, extra-axial...

Fig. 9: Right neck and occipital pain after a high intensity exercise. Unsteady gait,...

Fig. 10: Axial CT scan (Fig. A) reveals hyperdensity along the right V4 segment (solid...

Fig. 11: Fall with head injury

$Fig. 12: The caudal-most axial slice of the CT brain study (Fig. A) reveals an undisplaced fracture of the left lateral mass of the C1 vertebra (solid arrow). Axial (Fig. B) and sagittal (Fig. C) CT scan of the cervical spine confirm the findings (solid arrows).$

Fig. 12: The caudal-most axial slice of the CT brain study (Fig. A) reveals an...

Fig. 13: Known case of carcinoma of the lung. MRI brain was perfumed to look for...

Fig. 14: Axial DWI image (Fig. A) reveals a hyperintense lesion involving the...

Fig. 15: Young patient with recently diagnosed AML, presenting with neutropenic fever...

Fig. 16: Axial T2 image (Fig. A) reveals swelling and hyperintense signal within the...

Fig. 17: Giddiness and recurrent falls. MRI stroke screen to rule out stroke /...

Fig. 18: Axial DWI (Fig. A) and ADC (Fig. B) images obtained as a part of the stroke...

Fig. 19: Acute onset of left sided headache.

Fig. 20: Axial T2 image (Fig. A) reveals a abnormal flow void (solid arrow) adjacent to...

Fig. 21: Imaging performed for the evaluation of left hand tremor since 1 year, likely...

Fig. 22: Axial T2 image (Fig. A) reveals a partially imaged hyperintense mass in the...

Fig. 23: Incidental finding on a CT brain performed subacute functional decline.

Fig. 24: Axial CT image (Fig. A) shows a hypodense lesion in the left masticator space....

Fig. 25: Fall with head injury.

$Fig. 26: Axial CT scan using the bone algorithm (Fig. A) reveals a inferiorly located right mandibular head (solid arrow). Coronal facial bone scan (Fig. B, C) confirms a linear oblique fracture of the right hemimandibular ramus (solid arrows).$

Fig. 26: Axial CT scan using the bone algorithm (Fig. A) reveals a inferiorly located...

Fig. 27: Right upper and lower limb weakness.

Fig. 28: Axial T2 image (Fig. A) reveals a subtle hypointensity in the left...

Fig. 29: Incidental finding.

Fig. 30: Axial CT image (Fig. A) reveals a posterior dislocation of the right...

Findings and procedure details

Images are presented in a quiz format. Every single axial section demonstrates a pathology detected during reporting. Try to spot the abnormality on the image. Every single image is followed by a discussion with multiplanar / multimodality imaging.

Based on their location, pathologies in the last axial slice of the brain are:

1. INTRA-AXIAL LESIONS

Medullary infarct

Symptoms depend on the location. Lateral medullary (Wallenberg) syndrome presents with vertigo, nystagmus, and dysphagia. Horner syndrome, ataxia, loss of facial and taste sensation is seen ipsilaterally, while the loss of pain and temperature sensation in the arms and legs with minimal paresis is seen contralaterally. Medial medullary (Dejerine) syndrome causes ipsilateral hypoglossal palsy with contralateral hemiparesis and loss of vibration senses and proprioception (2-4).

Medullary cavernoma

These present with headache, ataxia, weakness or numbness of the face, arms and legs, and vomiting. At CT, they appear as hyperdense lesions due to blood/calcification. At MRI, cavernomas are reticulated, heterogeneous lesions with peripheral haemosiderin. Perifocal oedema and mass effect may be seen (5-7).

Chiari I malformation

Characterized by abnormal cerebellar tonsillar morphology with descent more than 2 age-adjusted SDs. Imaging reveals small posterior fossa, peg-shaped inferiorly located cerebellar tonsils, skull base anomalies and medullary kinking. Syringohydromyelia and hydrocephalus may be seen. Patients may be asymptomatic, some develop headache, paraesthesia or abnormal reflexes (8).

2. EXTRA-AXIAL LESIONS

Foramen magnum masses

Lesions at this location are rare. Clinical features include quadriparesis, headache, neck pain, or bowel-bladder disturbances. Common masses include meningiomas, schwannomas, metastasis, aneurysms and inflammatory masses (9, 10).

V4 dissection

Aetiologies include trauma, hypertension, oral contraceptives, or vascular diseases e.g. fibromuscular dysplasia. V4 dissection presents with severe headache, SAH and brainstem / cerebellar ischemia. Imaging of a V4 dissection may reveal increased external diameter, eccentric T1 high signal (mural haematoma) and luminal narrowing (11, 12).

3. CRANIOVERTEBRAL JUNCTION (CVJ)

CVJ trauma

CVJ injury commonly occurs after a high-velocity impact. Patients may present with neck pain or quadriplegia. On a brain scan, CVJ injuries may be difficult to detect, hence a high suspicion and dedicated spine imaging are crucial in appropriate cases (13,14).

CVJ metastasis

The cervical spine is the 2^nd most common location of spinal metastasis, after the thoracic spine. Common primaries include thyroid, lung, breast, renal, and prostate. Patients may present with neck pain, headache and neurological symptoms such as weakness. On MRI, lesions may appear as marrow signal alterations with/without soft-tissue masses (15).

4. REST OF THE PERIVERTERBAL SPACE

Prevertebral abscess

Prevertebral infection occurs due to local extension or hematogenous spread from the aerodigestive system, trauma, spinal osteomyelitis or inflammations (e.g. tendonitis). Symptoms include neck pain/stiffness, fever and/or dysphagia. A peripherally enhancing thick-walled collection with mass effect over the pharynx is seen on imaging (16).

5. PHARYNGEAL MUCOSAL AND PARAPHARYNGEAL SPACES

Nasopharyngeal carcinoma (NPC)

NPC occurs due to genetic susceptibility, carcinogen exposure or due to Epstein-Barr viral infection. The disease is may be silent, or present with epistaxis, nasal block, or cranial nerve palsies. NPCs demonstrate intermediate T2 signals and low T1 signals. Enhancement is lesser than normal mucosa. (17).

6. CAROTID SPACE

ICA dissection

Extracranial ICA dissection often affects the cervical segment, sparing the bulb. Dissections causing luminal occlusion lead to territorial ischemia, but those without luminal compromise may cause local symptoms like headache, neck pain and Horner syndrome. At imaging, dissections may be seen as a mural haematoma, intimal flap or dissecting aneurysm (18).

7. PAROTID SPACE

Parotid masses

Most lesions are slow-growing, presenting with a palpable lump or facial palsy. Benign and malignant masses can be discriminated using their MR features. Poorly defined, low T2 intensity and low ADC values generally indicate malignancy and vice versa (19).

8. MASTICATOR SPACE

Schwannoma

Schwannoma is the most common nerve sheath lesion in the masticator space. They are well defined, smooth, fusiform masses and enhance homogeneously. Larger lesions may be heterogeneous due to cystic degeneration or haemorrhage (20).

9. TEMPOROMANDIBULAR JOINT (TMJ)

TMJ TRAUMA

The mandible is among the most common sites of facial fractures. The angle and the condyles have thin cross-sections and are commonly fractured due to transmitted forces (21).

10. PTERYGOPALATINE FOSSA

Soft tissue lesions

The PPF follows fat density and signal on CT and MRI, respectively. Various neoplastic and non-neoplastic (infective/inflammatory) lesions involve the PPF. These extend by direct spread or via neurovascular connections from the head and neck (22).

11. ORBITS

Lens Injuries

The lens is suspended by the radial zonular fibres. Antero-posterior blunt forces to the globe tear these fibres causing partial or complete lens dislocation. Lens dislocation may also in connective tissue disorders (Marfan syndrome, Ehlers-Danlos syndrome) (23).