Callosal angle
Updates to Article Attributes
The callosal angle has been proposed as a useful marker of patients with idiopathic normal pressure hydrocephalus (iNPH), helpful in distinguishing these patients from those with ex-vacuo ventriculomegaly (see hydrocephalus versus atrophy).
It should be noted that there is nothing magical about this measurement, but rather it is merely a quantifiable measurement of the morphology of iNPH characterised by enlarged widening of the Sylvian fissures and cisterns with crowding of the gyri at the vertex.
MethodMeasurement
Ideally, the angle should be measured on a coronal image perpendicular to the anterior commissure - posterior commissure (AC-PC) plane at the level of thethe posterior commissure 1,2.
ValuesInterpretation
In general patients with iNPH have smaller angles than those with ventriculomegaly from atrophy or normal controls.
A normal value is typically between 100-120°. In patients with iNPH that value is lower, between 50-80° 2.
In one study, symptomatic iNPH patients who responded to shunting had a significantly smaller mean preoperative callosal angle (59° (95% CI 56°-63°)) compared with those who did not respond (68° (95% CI 61°-75°)) 1. Callosal angle cutoff value of 63° showed the best prognostic accuracy 3.
-<p>The <strong>callosal angle</strong> has been proposed as a useful marker of patients with <a href="/articles/normal-pressure-hydrocephalus">idiopathic normal pressure hydrocephalus (iNPH)</a>, helpful in distinguishing these patients from those with <a href="/articles/hydrocephalus-ex-vacuo">ex-vacuo ventriculomegaly</a> (see <a href="/articles/hydrocephalus-versus-atrophy-1">hydrocephalus versus atrophy</a>). </p><p>It should be noted that there is nothing magical about this measurement, but rather it is merely a quantifiable measurement of the morphology of iNPH characterised by enlarged widening of the Sylvian fissures and cisterns with crowding of the gyri at the vertex. </p><h4>Method</h4><p>Ideally the angle should be measured on a coronal image perpendicular to the <a href="/articles/anterior-commissure-posterior-commissure-line-1">anterior commissure - posterior commissure (AC-PC) plane</a> at the level of the <a href="/articles/posterior-commissure">posterior commissure</a> <sup>1,2</sup>.</p><h4>Values</h4><p>In general patients with iNPH have smaller angles than those with ventriculomegaly from atrophy or normal controls. </p><p>A normal value is typically between 100-120°. In patients with iNPH that value is lower, between 50-80° <sup>2</sup>. </p><p>In one study, symptomatic iNPH patients who responded to shunting had a significantly smaller mean preoperative callosal angle (59° (95% CI 56°-63°)) compared with those who did not respond (68° (95% CI 61°-75°)) <sup>1</sup>. Callosal angle cutoff value of 63° showed the best prognostic accuracy <sup>3</sup>.</p>- +<p>The <strong>callosal angle</strong> has been proposed as a useful marker of patients with <a href="/articles/normal-pressure-hydrocephalus">idiopathic normal pressure hydrocephalus (iNPH)</a>, helpful in distinguishing these patients from those with <a href="/articles/hydrocephalus-ex-vacuo">ex-vacuo ventriculomegaly</a> (see <a href="/articles/hydrocephalus-versus-atrophy-1">hydrocephalus versus atrophy</a>). </p><p>It should be noted that there is nothing magical about this measurement, but rather it is merely a quantifiable measurement of the morphology of iNPH characterised by enlarged widening of the Sylvian fissures and cisterns with crowding of the gyri at the vertex. </p><h4>Measurement</h4><p>Ideally, the angle should be measured on a coronal image perpendicular to the <a href="/articles/anterior-commissure-posterior-commissure-line-1">anterior commissure - posterior commissure (AC-PC) plane</a> at the level of the <a href="/articles/posterior-commissure">posterior commissure</a> <sup>1,2</sup>.</p><h4>Interpretation</h4><p>In general patients with iNPH have smaller angles than those with ventriculomegaly from atrophy or normal controls. </p><p>A normal value is typically between 100-120°. In patients with iNPH that value is lower, between 50-80° <sup>2</sup>. </p><p>In one study, symptomatic iNPH patients who responded to shunting had a significantly smaller mean preoperative callosal angle (59° (95% CI 56°-63°)) compared with those who did not respond (68° (95% CI 61°-75°)) <sup>1</sup>. Callosal angle cutoff value of 63° showed the best prognostic accuracy <sup>3</sup>.</p>
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