Supratentorial Vascular Anatomy




Fig. 3.3 Anterior choroidal artery and lenticulostriate arteries. These are best seen here without overlap from branches of the middle cerebral artery in a patient with complete occlusion of the MCA bifurcation. Lateral projection

A420739_1_En_3_Figb_HTML.jpg



3.1.1.2 Internal Carotid Artery Pathology


Occlusion syndromes of ICA



  • Contralateral hemiplegia and hemianesthesia


  • Deviation of the gaze toward of the lesion.


  • Homonymous hemianopsia (superior 1/2 of the optic radiation)


  • Carotid dissections may cause Bernard-Horner syndrome. The syndrome is characterized by damage to the carotid sympathetic plexus causing a prevalence of parasympathetic innervation resulting in ptosis, miosis, enophthalmos, and rarely facial anhydrosis of the same side of the dissection.


  • Dominant hemispheric lesion: Broca’s aphasia if the superior division of the MCA is thrombosed; Wernicke’s aphasia if the inferior division of the MCA is occluded.


  • Nondominant hemispheric lesion: contralateral hemineglect, hemiinattention, tactile extinction, visual extinction, anosognosia, and apraxia.

Specific artery occlusions:



  • Lenticulostriate arteries → pure motor hemiparesis.


  • Artery of the angular gyrus → agnosia, acalculia, agraphia, disorientation.


  • Ophthalmic artery → amaurosis.


  • In case of absent collateral compensation from the anterior communicating artery, symptoms arising from anterior cerebral artery occlusions may concur.


  • Occlusion of the carotid siphon, with valid MCA collateral flow, neurologic deficit due to occlusion of the anterior choroidal artery may be present together with amaurosis.


  • Anterior choroidal artery → hemiparesis (posterior limb of the internal capsule), hemianesthesia (posterolateral nuclei of the thalamus), and hemianopsia (lateral geniculate bodies). In case of bilateral occlusions (rare), get pseudobulbar mutism, diplegia, lethargy, and neglect.



3.1.2 Anterior Cerebral Artery



3.1.2.1 Cortical Territory


The ACA provides the medial surface of the frontal and parietal lobes including the precuneus posteriorly. Cortical branches reach the outer surface of the brain to reach cortical branches of the MCA (pial anastomosis). Five segments can be identified on DSA imaging (Figs. 3.4 and 3.5).


  1. I.


    A1 segment (supraoptic): It gives rise to deep perforating arteries (see below).

     

  2. II.


    A2 segment (infracallosal).


    1. (a)


      Fronto-orbital artery: medial region of the orbital surface of the frontal lobe

       

    2. (b)


      Frontopolar artery: for the frontal pole

       

     

  3. III.


    A3 segment (precallosal): At the level of the genu of the corpus callosum ACA. It presents the pericallosal/callosomarginal bifurcation.


    1. (a)


      Pericallosal artery.


      1. i.


        Artery for the paracentral lobule

         

      2. ii.


        Anterior internal parietal artery

         

      3. iii.


        Anterior posterior internal parietal artery

         

       

    2. (b)


      Callosomarginal artery: It arises from the A2 to A3 segment at the level of the genu of the corpus callosum. It supplies the frontal cortical territory in front of the paracentral lobule on the medial surface of the frontal lobe. Here it gives rise to three internal frontal arteries (anterior, middle, and posterior).

       

     

  4. IV.


    A4 and A5 segments (supracallosal):


    1. (a)


      Superior internal parietal artery

       

    2. (b)


      Inferior internal parietal artery

       

     

The ACA might end with an anastomosis with the PCA through the splenial artery.


3.1.2.2 Deep Territory of A1


From the A1 segment of ACA originate, a number of perforating arteries that supply the diencephalon and the subcallosal region by penetrating the anterior perforated substance, reaching the globus pallidus and the head of the caudate nucleus. The main branches are:



  • Midline perforators or diencephalic perforators: provide vascular supply to the septum pellucidum, anterior hypothalamus, fornix, lamina terminalis, anterior commissure, rostrum, and genu of the corpus callosum.


  • Perforating arteries of the anterior perforated substance or the medial lenticulostriate arteries: provides vascular supply to the anteroinferior region of the lenticular nucleus, the anteroinferior portion of the caudate nucleus, and the anterior limb of the internal capsule.


  • Recurrent artery of Heubner: is a perforating artery that originates at the junction of A1–A2 segments of the anterior cerebral artery and provides arterial supply to the head of the caudate nucleus, the inferior portion of the internal capsule (jointly with the medial lenticulostriate arteries), and the hypothalamus (jointly with the medial lenticulostriate arteries and the subcallosal perforators of A1).


3.1.2.3 Anterior Cerebral Artery Pathology


Occlusion syndromes of ACA



  • Hemiparesis and hemianesthesia of the contralateral lower limb


  • Abulia with bilateral lesions of the cingulum


  • Akinetic mutism (bilateral fronto-mesial lesions)


  • Memory loss


  • Apathy


  • Transcortical motor aphasia


  • Head and gaze deviation toward the side of the lesion


  • Paratonia


  • Loss of capacity of discriminative touch and proprioception


  • Urinary incontinence and other vegetative symptoms (e.g., diabetes insipidus)

Specific artery occlusions:



  • Pericallosal artery → apraxia, agraphia, and tactile anomia of the left hand


  • ACA azygos → paraparesis with or without loss of sensation


  • Subcallosal artery → anterograde amnesia, anxiety, and psychomotor agitation


  • Recurrent artery of Heubner → facial hemiparesis and loss of tactile sensation

Fig. 3.4 Anterior cerebral artery and anterior choroidal artery, best seen in the absence of contrast medium in the middle cerebral artery territory due to occlusion of the distal portion of the M1 segment. Lateral projection

Fig. 3.5 Anatomic variant with dominant callosomarginal artery, best seen in the absence of contrast medium in the middle cerebral artery territory due to occlusion of the distal portion of the M1 segment. Lateral projection

A420739_1_En_3_Figc_HTML.gif

Fig. 3.6 Recurrent artery of Heubner, lenticulostriate perforators, and perforators of the insular segment of MCA. Anteroposterior projection

Fig. 3.7 Lenticulostriate arteries and bilateral recurrent artery of Heubner, better seen due to the complete occlusion of the M1 segment of the MCA. Anteroposterior projection

A420739_1_En_3_Figd_HTML.gif


3.1.3 Middle Cerebral Artery



3.1.3.1 Cortical Territory


The middle cerebral artery (MCA) provides the temporal lobe, insular cortex, lateral aspects of the frontal lobe and the basal ganglia. It can be subdivided into four different segments (Figs. 3.8, 3.9 and 3.10).


  1. I.


    M1 segment (sphenoidal or horizontal):


    1. (a)


      Lateral lenticulostriate arteries: supply the anterior deep gray matter nuclei (pallidum, putamen, caudate nuclei), internal capsule, adjacent fibers of the corona radiata

       

    2. (b)


      Anterior temporal artery

       

     

  2. II.


    M2 segment (insular): it lies on the insular surface from the genu to the circular sulcus. Between M1 and M2 segment the MCA bifurcates (and sometimes trifurcates) in its main branches:


    1. (a)


      Superior branch (frontal opercular branch): this gives rise to prefrontal artery, precentral artery, and central artery.

       

    2. (b)


      Inferior branch (temporal opercular branch): this artery gives rise to the anterior, the middle and the posterior temporal arteries, temporo-occipital artery, and the angular gyrus artery.

       

    3. (c)


      Also, insular medullary perforating arteries (vascular supply to the external regions of the putamen, external capsule, and the claustrum) arise from M2 segment.

       

     

  3. III.


    M3 segment (opercular): it extends from the turn at the level of the circular sulcus to the turn at the Sylvian fissure.

     

  4. IV.


    M4 segment (cortical) starts from the superficial part of the Sylvian fissure and its branches are identified by the name of the sulci they lie in.

     


3.1.3.2 Deep Territory


From the M1 segment of the MCA originate a number of perforating arteries that supply the putamen, the lateral portion of the globus pallidus, the body of caudate nucleus, the superior part of the internal capsule, the lateral part of the anterior commissure, and the substantia innominata. The main branches are (Figs. 3.6, 3.7 and 3.11):



  • Lateral lenticulostriate arteries may be further grouped into a medial group (in the proximity of the origin of M1), an intermediate group that arise from the middle third of M1, and a more lateral group that arises from the M1–M2 junction (Fig. 3.7).


  • Insular medullary perforating arteries arise from M3, and they typically distribute similarly to the cortical medullary arteries in the depths of the insular cortex to provide vascular supply to the external regions of the putamen, the external capsule, and the claustrum.


3.1.3.3 Middle Cerebral Artery Pathology


Occlusion syndromes of the MCA



  • Contralateral hemiplegia and hemianesthesia


  • Deviation of gaze toward the lesion


  • Homonymous hemianopsia (superior one-half of the optic radiation)


  • Dominant hemisphere MCA occlusion



    • Superior division: Broca’s aphasia


    • Inferior division: Wernicke’s aphasia


  • Nondominant hemisphere: hemineglect, hemiinattention, tactile extinction, visual extinction, anosognosia, and apraxia


  • Lenticulostriate arteries: pure motor hemiparesis


  • Angular gyrus artery: agnosia, acalculia, agraphia, and spatial disorientation

Fig. 3.8 Segments of the middle cerebral artery. Anteroposterior projection

Fig. 3.9 Cortical branches of the middle cerebral artery. Best seen in this patient with congenital agenesis of A1 segment of the ipsilateral anterior cerebral artery. Lateral projection
Tags:
Dec 24, 2017 | Posted by in NEUROSURGERY | Comments Off on Supratentorial Vascular Anatomy

Full access? Get Clinical Tree
Get Clinical Tree app for offline access