Head & neck imagingCase Type
Bhavna Arora, Vineet Mishra, Anoop VarmaPatient
62 years, male
A 62-year-old hypertensive man presented to the neurology clinic with history of swallowing difficulty characterized by a sensation that the right side of his throat “could not bring things down.” Patient neglected his problem for over a month and took it seriously only a few days back, for which the MRI scan was conducted. Patient does not give any history of deacceleration trauma, physiotherapy or any manipulation of neck.
T1/ T1-post contrast and T2 image shows crescentic to asymmetric circumferential area of hyperintensity overlying the cervical portion of the internal carotid artery with adjacent narrowing of the flow-related signal void (suggesting late subacute stage of intramural blood). The lesion is compressing the exiting hypoglossal nerve from hypoglossal canal on ipsilateral side.
T2 fat sat image show hyperintensity in ipsilateral half of tongue with minimal atrophy with falling back of tongue in the oropharynx on the same side.
Arterial dissections are potentially disabling conditions characterized by tear in intimal layer with collection of blood between layers of vessel. When the dissection extends toward the adventitia, it can form a protrusion from the weakened vessel wall called a pseudoaneurysm, which may become a nidus for distal thromboembolism or cause mass effect on adjacent structures. [1,2]
Cranio-cervical dissections account for comorbidities in both young and adult population - could be spontaneous or traumatic. Major complications like stroke, haemorrhage can be prevented if timely diagnosis is made and intervention is done. [3,4]
Aneurysmal dilatation can also cause a mass effect on nearby structures such as sympathetic fibres and the lower cranial nerves. Isolated hypoglossal nerve involvement is a rare phenomenon. 
Headache, neck pain, or scalp tenderness, sequelae can be catastrophic and include stroke, haemorrhage, or death (due to ICA dissection).
Dysarthria, a mild tongue movement impairment,dysphagia (due to hypoglossal nerve involvement).
CT angiography: for visualisation of intramural hematoma and eccentric true lumen.
In the acute and subacute setting, T1 fat-suppressed imaging of the neck is the sequence used for diagnosis of internal carotid artery dissection with intramural blood, usually in a crescent shape, demonstrating high signal intensity with adjacent narrowing of the flow-related signal void. T2 hyperintense intramural signal suggests subacute stage.
MRA (with contrast) imaging reveals narrowing of true lumen by the hematoma.
Changes of nerve involvement due to compression by pseudoaneurysm- T2 hyperintensity of ipsilateral tongue with falling back of tongue in oropharynx (in congruence to subacute stage of intramural blood).
Systemic anticoagulation (treatment of choice). Endovascular stenting /balloon dilation (persistent symptoms).
Take-Home Message / Teaching Points
ICA dissections leading to pseudoaneurysm formation is a common entity. However, compression of hypoglossal nerve by this pseudoaneurysm causing symptoms of compression is a rare presentation. Careful analysis of adjacent nerves and imaging features of nerve compression can help fetch the complete diagnosis.
Written informed patient consent for publication has been obtained.
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