Uncal herniation

Changed by Bruno Di Muzio, 21 Jan 2015
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Uncal herniation is a subtype of transtentorial downward brain herniation, usually related to cerebral mass effect increasing the intracranial pressure.

​Clinical presentation

Abnormal posture and poor GCS. There may be pupillary dilation and loss of light reflex due to direct compression of the oculomotor nerve. 

Pathology

In uncal herniation, the uncus and adjacent part of the temporal lobe glide downward across the tentorial incisura compressing the brainstem and the posterior cerebral arteries in the ambient cistern. Uncal herniation may unilateral or bilateral 1,2.

Aetiology

Uncal herniation occurs secondary to large mass effect (that can occur from traumatic or non-traumatic haemorrhage, malignancy, etc) that will lead to increased intracranial pressure and herniation.

Radiographic features

CT

Uncal herniation can be suggested on CT but MRI, however MRI is the gold standard. Mass effect and obliteration of the suprasellar cistern will be seen. The midbrain is displaced and effaced. 

MRI

Unilateral transtentorial herniation:

  • more common type

  • uncus and medial temporal lobe displaced medially causing effacement of the suprasellar cistern if mild
  • hippocampus will obliterate the quadrigeminal cistern in moderate transtentorial herniation

Bilateral transtentorial herniation:

  • occurs due to extensive mass effect or severe trauma that is why less common

  • both temporal lobes herniated into tentorial incisura
  • total obliteration of suprasellar cistern 
  • midbrain effaced and displaced inferiorly

Treatment and prognosis

Uncal herniation carries a bad prognosis due to the direct compression of the vital midbrain centers. They often require emergent neurosurgicalemergency neurosurgical decompression. 

Complications 

Practical points

  • if uncal herniation is diagnosed, the results should be phoned through to the referrer immediately
  • -<p><strong>Uncal herniation</strong> is a subtype of transtentorial downward <a href="/articles/brain-herniation">brain herniation</a>.</p><h4>​Clinical presentation</h4><p>Abnormal posture and poor GCS. There may be pupillary dilation and loss of light reflex due to direct compression of the oculomotor nerve. </p><h4>Pathology</h4><p>In uncal herniation, <a href="/articles/the-uncus">the</a><a href="/articles/the-uncus"> uncus</a> and adjacent part of the <a href="/articles/temporal-lobe">temporal lobe</a> glide downward across the tentorial incisura compressing the brainstem and the posterior cerebral arteries in the ambient cistern. Uncal herniation may unilateral or bilateral <sup>1,2</sup>.</p><h5>Aetiology</h5><p>Uncal herniation occurs secondary to large mass effect (that can occur from traumatic or non-traumatic haemorrhage, malignancy, etc) that will lead to increased intracranial pressure and herniation.</p><h4>Radiographic features</h4><h5>CT</h5><p>Uncal herniation can be suggested on CT but MRI is the gold standard. Mass effect and obliteration of the suprasellar cistern will be seen. The midbrain is displaced and effaced. </p><h5>MRI</h5><h6>Unilateral transtentorial herniation </h6><ul>
  • -<li>more common type</li>
  • +<p><strong>Uncal herniation</strong> is a subtype of transtentorial downward <a href="/articles/brain-herniation">brain herniation</a>, usually related to cerebral mass effect increasing the intracranial pressure.</p><h4>​Clinical presentation</h4><p>Abnormal posture and poor <a href="/articles/glasgow-coma-scale">GCS</a>. There may be pupillary dilation and loss of light reflex due to direct compression of the <a href="/articles/oculomotor-nerve">oculomotor nerve</a>. </p><h4>Pathology</h4><p>In uncal herniation, <a href="/articles/the-uncus">the</a><a href="/articles/the-uncus"> uncus</a> and adjacent part of the <a href="/articles/temporal-lobe">temporal lobe</a> glide downward across the tentorial incisura compressing the brainstem and the posterior cerebral arteries in the <a href="/articles/ambient-cistern">ambient cistern</a>. Uncal herniation may unilateral or bilateral <sup>1,2</sup>.</p><h5>Aetiology</h5><p>Uncal herniation occurs secondary to large mass effect (that can occur from traumatic or non-traumatic haemorrhage, malignancy, etc) that will lead to increased intracranial pressure and herniation.</p><h4>Radiographic features</h4><p>Uncal herniation can be suggested on CT, however MRI is the gold standard. Mass effect and obliteration of the suprasellar cistern will be seen. The midbrain is displaced and effaced. </p><h5>MRI</h5><p>Unilateral transtentorial herniation:</p><ul>
  • +<li><p>more common type</p></li>
  • -</ul><h6>Bilateral transtentorial herniation</h6><ul>
  • -<li>occurs due to extensive mass effect or severe trauma that is why less common</li>
  • +</ul><p>Bilateral transtentorial herniation:</p><ul>
  • +<li><p>occurs due to extensive mass effect or severe trauma that is why less common</p></li>
  • -</ul><h4>Treatment and prognosis</h4><p>Uncal herniation carries a bad prognosis due to the direct compression of the vital midbrain centers. They often require emergent neurosurgical decompression. </p><h5>Complications </h5><ul>
  • +</ul><h4>Treatment and prognosis</h4><p>Uncal herniation carries a bad prognosis due to the direct compression of the vital midbrain centers. They often require emergency neurosurgical decompression. </p><h5>Complications </h5><ul>

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