Correct
Case 72
【Progress】He was given antihypertensive agent and educated to take it routinely. He agreed to take rehabilitation in admission, leading to gradually improve motor nerve function.
【Discussion】
Internal capsule is a white matter and the one of the main routes connected between cerebral cortex and brain stem. It is a relay station between cerebrum cortex and brain stem. It largely constitutes of five components: anterior limb, genu, posterior limb, retrolenticular part and sublenticular part (1). Anterior limb connects between frontal cortex and cerebellum, and between frontal cortex and thalamus (cerebellum take all information from cerebrum and thalamus stimulates to whole cerebrum when awaking in the morning). They are called frontopontine track and anterior thalamic track, respectively. Further, anterior limb contains the route between caudate nucleus head and striate body (globus pallidus) like a bridge.
Genu and posterior limb include pyramidal tract. Nerve axons of pyramidal tract travel from motor cortex to cerebral peduncle via internal capsule, pons and anterior medulla and anterior spinal cord. They are called corticospinal tract.
Pyramidal tract of genu mainly connects between facial motor nerve related with eye, mouth and face movement and cerebrum motor cortex (precentral cortex). Extrapyramidal tract passes along with pyramidal tract.
Pyramidal tract of posterior limb connects between motor nerve of upper and lower extremities, and cerebral motor cortex (precentral cortex). Somatosensory tract is present at the dorsal side of pyramidal tract in the posterior limb.
Retrolenticular part connects to optic radiation, from optic nerve to visual cortex.
Sublenticular part connects to auditory radiation, from auditory nerve to auditory cortex.
In our case, diffusion MRI showed high signal intensity at genu and posterior limb which caused weakness of upper and lower extremities, implying is chemic damage of corticospinal tract.
Blood supply of internal capsule is perforating arteries largely from anterior cerebral artery, middle cerebral artery and anterior choroidal artery. Namely, anterior limb is blood-supplied from medial striate branch artery from anterior cerebral artery, and lateral striate artery and lenticulostriate artery from middle cerebral artery. Genu and a frontal part of posterior limb is blood-supplied by lateral striate artery and lenticulostriate artery from middle cerebral artery. Posterior limb is mainly blood-supplied from anterior choroidal artery from internal carotid artery, retrolenticular part and sublenticular part are blood-supplied from anterior choroidal artery (2). These perforating arteries are susceptible to occlusion or hemorrhage due to atherosclerosis or hypertension.
When anterior limb was stroke-damaged, the ischemic symptoms are largely silent or dysarthria due to a damage of frontal lobe tract. The most frequent lacunar stroke is pure motor hemiparesis caused by damages of posterior limb, corona radiata or basilar part of pons (3, 4). The second most frequent lacunar infarct is ataxic hemiparesis caused by damages of posterior limb including pyramidal tract, extrapyramidal tract and somatosensory tract, corona radiata or basilar part of pons and basal ganglia (3, 4). The stroke of retrolenticular part and/od sublenticular part rarely happens. Our patient experienced weakness of upper and lower extremities, indicative of pure motor hemiparesis.
Diffusion weighted image (DWI) and apparent diffusion coefficient (ADC) map are commonly used for detection of early brain infarction. ADC reduction occurs after a few minutes and ADC decreases with maximal signal reduction at 1 to 4 days (5, 6). Subsequently, ADC is getting elevated because vasogenic edema from extravasation of water molecule from vessels to expand interstitial space where water molecule is no longer restricted. Meanwhile, high signal intensity of DWI which is affected by combination of T2 and diffusion weighting, occurs after a few minutes and remains for a couple of weeks (5, 6). Conventional MRI sequences of T1WI and T2WI might not demonstrate an infarct for at least 6 hours (5, 6). In our case, DWI and T2WI showed high signal intensity corresponded to lacunar infarcts of internal capsule.
Stroke rehabilitation is an important part of recovery of brain stroke. The sooner a patient initiates stroke rehabilitation, the more likely the patient is able to regain the lost abilities and skills. After confirmed stabilization of medical condition and prevention of another stroke, stroke rehabilitation starts as soon as 24 to 48 hours after stroke (7, 8). In our case, he was given antihypertension agent and rehabilitation started two days after stroke.
【Summary】
We present a forty four-year-old male with sudden weakness of left upper and lower extremities. He had no treatment for hypertension. MRI showed high signal intensity at right-sided genu and posterior limb of internal capsule on DWI and T2WI which implies acute infarction of corticopontine tract in the genu and corticospinal tract in the posterior limb. We should keep in mind that internal capsule had five components; anterior limb, genu, posterior limb, retrolenticular part and sub lenticular part. The genu and posterior limb contains pyramidal tract, extrapyramidal tract, and somatosensory tract which were blood-supplied by perforating arteries of lateral striate branch artery and lenticulostriate branch artery from middle cerebral artery. The earlier rehabilitation of stroke rehabilitation within two days is likely to bring about recovery of the lost ability and skill.
【References】
1.Rea P. Essential Anatomy and Function of the Brain. 2015
2.Vitosević Z, Cetković M, Vitosević B et-al. Blood supply of the internal capsule and basal nuclei. Srp Arh Celok Lek. 2005;133 (1-2): 41-5.
3.Marta GO (2007). "Neuropsychological abnormalities associated with lacunar infarction". Journal of the Neurological Sciences. 2007; 257 (1–2): 160–5. PMID 17316693. doi:10.1016/j.jns.2007.01.022.
4.Longstreth Jr, W. T, et al. . "Lacunar infarcts defined by magnetic resonance imaging of 3660 elderly people: The Cardiovascular Health Study". Archives of Neurology. 1998 55 (9): 1217–25. PMID 9740116. doi:10.1001/archneur.55.9.1217.
5.Srinivasan A, Goyal M, Al azri F et-al. State-of-the-art imaging of acute stroke. Radiographics. 2006;26 Suppl 1 : S75-95. doi:10.1148/rg.26si065501 - Pubmed citation
6.Allen LM, Hasso AN, Handwerker J et-al. Sequence-specific MR Imaging Findings That Are Useful in Dating Ischemic Stroke. Radiographics. 2012;32 (5): 1285-97. doi:10.1148/rg.325115760 - Pubmed citation
7.Daroff RB, et al. Neurological rehabilitation. In: Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, Pa.: Saunders Elsevier; 2016. https://www.clinicalkey.com. Accessed March 28, 2017.
8.Bope ET, et al. The nervous system. In: Conn's Current Therapy 2017. Philadelphia, Pa. Elsevier; 2017. https://www.clinicalkey.com. Accessed March 28, 2017.
2017.9.20