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The Internal Capsule Is One of the Subcor 8/24/2015 Joint Commission Technical Advisory Panel (TAP) for Comprehensive Stroke Centers – no monetary benefits Debbie Summers, MSN, RN, ACNS-BC, CNRN, SCRN, FAHA, ANVP Evaluates the structures of the internal Contains all of the capsule and related cerebral blood supply pathways that Compare and contrast the classical lacunar allow information syndromes and what differentiates deficits to be transferred between subcortical and cortical between: Summarizes the clinical significance of subtle ◦ the cerebral cortex to clinically silent symptoms associated with and the spinal cord, lacunar strokes brainstem and subcortical structures The internal It is divided into an capsule is one of a. Anterior limb the subcortical b. Posterior limb structures of the c. Genu (or knee) brain. 1 8/24/2015 White arrows point to the Caudate internal capsule nucleus Black arrow points to the (Ganglia gray genu Right anterior matter) C – Caudate Nucleus limb, internal G - Globus pallidus capsule Lentiform (White Nucleus P – Putamen (Lentiform matter) (Ganglica Nucleus) gray matter) T – thalamus Left Lateral ventricles are posterior white Thalamus limb, (gray internal matter) capsule (White matter) The sensory tract (blue) formed of neurons receiving impulses from below into thalamus and transmitted to the cortex (somatosensory pathways) Motor tract (red) The optic radiation (occipito- thalamic) (violet) SAME Sensory Afferent – Ascending Motor Efferent – Descending Internal Capsule Basal ganglia Basal Ganglia The function of the basal ganglia in motor control is ◦ caudate nucleus striatum (caudate not understood in detail ◦ putamen nucleus and ◦ nucleus accumbens putamen) •The basal ganglia allow you to automatically (or ventral striatum) perform a learned motor behavior •From your motor memory, basal ganglia facilitates ◦ globus pallidus in preparing for motor action ◦ lentiform nucleus •It controls and modifies your movements •It is one of the brain structures that maintain Subsubstantia nigra posture Thalamus •Basal ganglia play a role in memory retrieval 2 8/24/2015 It is a continuous sheet of fibers that forms the medial boundary of the lenticular nucleus It continues around posteriorly and inferiorly to partially envelop this nucleus Inferiorly many of the fibers of the internal capsule funnel into the cerebral peduncles Anterior limb separates the caudate nucleus and lenticular nucleus Posterior limb separates the thalamus and lentiform nucleus Contains axons: Tracts: ◦ That send ◦ Thalamocortical information between fibers (thalamus to the thalamus and the frontal lobe) cingulate gyrus and pre-frontal cortex ◦ That send ◦ Frontopontine fibers information from the (frontal cortex to frontal cortex to the pons) pons 3 8/24/2015 Contains axons Tracts: ◦ Originate in the motor ◦ Corticobulbar fibers (cortex areas of the frontal to brainstem) lobes and extend to the cranial nerve nuclei in the brainstem ◦ Ventral anterior (VA) and ◦ Connect the motor Ventral lateral (VL) nucleus section of the thalamus receives information from with the motor areas of the cerebellum and globus the frontal cortex pallidus that pass into the premotor cortex for initiation and planning of movement) Contains axons: Corticospinal tract ◦ That come from the motor area of the frontal cortex and extend to the anterior horns of the Posterior (dorsal) spinal cord column-medial lemniscus pathway - ◦ Contains sensory touch, vibration, two- information coming from point discrimination the body and proprioception Anterior lateral (Spinothalamic tract) Lenticulostriate arteries, small Left MCA Right pure upper-motor hemiparesis arteries Lenticulostriate due to damage to the basal ganglia Branches (globus pallidus and striatum) and originate from the genu of the internal capsule on the first the left side portion of the MCA (supplies Right MCA Left pure upper-motor anterior limb Lenticulostriate hemiparesis due to damage to the and genu) Branches basal ganglia (globus pallidus and striatum) and the genu of the internal capsule on the right side 4 8/24/2015 Anterior choroidal artery – branch of ICA supplying the inferior portion of the posterior limb Portions of the thalami (specifically the lateral geniculate nuclei and ventral posterolateral nuclei) Hemiparesis Corticospinal tracts (weakness on the Optic tracts portion opposite side) Middle third of the cerebral peduncles Posterior (dorsal) Portions of the temporal lobes (ie: parts of the Hemianesthesia column-medial pyriform cortex, uncus, and amygdala) lemniscus Substantia nigra Homonymous Optic tracts and Portions of the globus pallidus hemianopsia lateral geniculate Choroid plexus in the lateral ventricles nucleus of the thalamus Noted involving the posterior limb of right internal capsule as well as the head of the right hippocampus MRI CT Head 5 8/24/2015 Recurrent artery of Heubner is a branch of the ACA. It supplies the inferior portions of the anterior limb, the genu and head of caudate There is loss of substance in the head of Infarction results in prominent motor and the caudate, anterior neuropsychological putamen and anterior ◦ Contralateral weakness of the face and arm findings limb of the internal ◦ Cognitive and behavioral abnormality – confusion capsule consistent ◦ Linguistic abnormalities, frontal system with infarction in the dysfunction, and amnesic deficits territory of right recurrent artery of Heubner (RHA). Supplies the head of caudate, anterior portion of the lentiform nucleus and anterior limb of the internal capsule. This patient had an ACOM aneurysm clipped. ◦ Either sacrificed with clipping or with vasospasm it occurred 6 8/24/2015 The original pathological descriptions of About 20 % of all strokes. lacunar infarcts were made by the beginning Common in hypertension and diabetes of this century Small vessel disease includes atherosclerosis Lacunar infarcts vary from 3-20 mm, and are of small arteries but refers more specifically most commonly found in the putamen to lipohyalinosis and hyaline (lentiform), caudate, thalamus, pons, internal atreriolosclerosis, vascular lesions that are capsule and cerebral white matter, in seen primarily in hypertension and diabetes descending order of frequency Weakness of the face, arm, and/or leg (pure Mixed sensorimotor stroke motor stroke) ◦ Since both motor and sensory fibers are carried in Pure motor stroke caused by an infarct in the internal the internal capsule, a stroke to the posterior limb capsule is the most common lacunar syndrome. of the internal capsule (where motor fibers for the ◦ Upper motor neuron signs – hyperreflexia, Babinski, arm, trunk and legs and sensory fibers are located) clonus spasticity and Hoffman present can lead to contralateral weakness and contralateral sensory loss 7 8/24/2015 If a patient has What other weakness +/- symptoms or signs sensory deficits, how can help you can you tell whether localize the stroke the stroke to the internal subcortical or cortica capsule as opposed l to the cortex? A patient who presents with arm and leg weakness may have either a small internal capsule stroke or a large ACA + MCA cortical stroke Looking at the homunculus, the cortical leg area is supplied by the ACA and the arm area is supplied by the MCA The presence of these cortical signs may A vascular lesion of exclude an internal capsule stroke: the visual cortex is ◦ gaze preference or gaze deviation likely to result in a ◦ expressive or receptive aphasia quadrantic defect ◦ visual field deficits and/or macular ◦ visual or spatial neglect sparing 8 8/24/2015 Name Location Presentation Pure motor Posterior limb It is marked by hemipareis or Stroke (most hemiplegia that typically affects the common lacunar Basis pontis face, arm, or leg of one side. syndrome: 33- (anterior Dysarthria, dysphagia, and transient 50%) portion), corona sensory symptoms may also be radiata present. Ataxic Posterior limb It displays a combination of cerebellar hemiparesis and basis pontis and motor symptoms, including (second most weakness and clumsiness, on the frequent lacunar Corona radiata, ipsilateral side of the body. syndrome) red nucleus, lentiform It usually affects the leg more than it nucleus, does the arm; hence, it is known also Superior as homolateral ataxia and crural Cerebellar Artery paresis. The onset of symptoms is (SCA) and often over hours or days. Anterior Cerebella Artery (ACA) infarcts Name Location Presentation Name Location Presentation Dysarthria/clumsy Anterior limb The main symptoms are Mixed Thalamus and This lacunar syndrome involves hand (sometimes dysarthria and clumsiness of one sensorimot adjacent hemiparesis or hemiplegia with considered a Basis pontis, or hand (weakness) plus or minus or stroke posterior internal ipsilateral sensory impairment variant of ataxic genu of internal central facial paralysis, which capsule, lateral hemiparesis, but capsule, corona often are most prominent when pons usually still is radiata, basal the patient is writing classified as a ganglia, •If central facial paralysis separate lacunar thalamus, • Dysphagia syndrome) cerebral • Tongue deviation peduncle Pure sensory Contralateral Marked by persistent or transient stroke thalamus, numbness, tingling, pain, internal capsule, burning, or another unpleasant corona radiata, sensation on one side of the body midbrain •absent of motor weakness, visual symptoms, or imbalance 1. Memory impairment 2. Dementia 3. Cognitive impairment 4. Emotional disturbance 9 8/24/2015 Very small lesions
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