Clinical diagnosis
Case 164
【Progress】
Day by day rehabilitation brought her prompt improvement of left hemiparesis. But her hypofunction of left masseteric muscle and mouth angle, and disorder of high grade brain function including hypo-attention power still remained.
【Discussion】
Brain artery occlusion is largely two types: embolism and thrombosis. Embolism occurs by flying thrombotic or bacterial substance arising from heart or large carotid artery. Thrombosis occurs by the origin of brain artery itself. As pathogenesis with occlusive brain artery, accumulation of atheroma, fibrinoid deposition, amyloid accumulation and granular deposition in the arterial wall are listed (1, 2). The disease of amyloid accumulation is termed as cerebral amyloid angiopathy (CAA), and that of granular deposition is termed as cerebral autosomal dominant arteriopathy subcortical infarction and leukoencephalopathy (CADASIL)(1 – 4).
Atherosclerotic change of the brain artery is a little different among large artery, medium-sixzed artery and small artery (5). In a large artery and medium-sized artery, atheroma composed of cholesterol, low density lipoprotein (LDL) and plasma component like apoprotein E is eventually formed between endothelium (with rupture of elastic fiber) and smooth muscle. Initially macrophages phagocyte oxidized LDL which are called foam cells and accumulate in the intima. When foam cells dye, their contents are released, inducing to attract more macrophages. This process is repeated, leading to the atheroma formation.
This process does not always advance in small arteries, but it stays at the accumulation of foam cells before atheroma formation probably because of the less volume of oxidized LDL (5). In smaller brain arteries, lipohyalinosis occurs. It composes of fibrinoid necrosis and thickened media containing lipohyalinotic material. The change of lipohyalinosis is found in the vessel wall of small arteries of 40 to 200 µm, while the change of intimal micro-atheroma is found in those of 300 to 500 µm (6, 7). It is believed that lacunar infarction arises from occlusion of a part of perforating artery due to lipohyalinosis (6, 7). Branch atheromatous disease (BAD) arises from occlusive disease of total perforating artery due to micro-atheroma (5).
BAD induces worsening ischemic symptoms and expanding the ischemic lesion larger with time than lacunar infarction. There are two theories why the lesion is expanding with time; one is that lipohyalinosis induces not only antegrade occlusion but also retrograde occlusion as time progress: another is that micro-atheroma exists and gradually grows in a parent artery, exists and occlude gradually at the junctional micro-atheroma, or exists and occlude at the orifice of perforating artery. Now, the latter theory is getting supported because of the several pathological evidence (5).
BAD is known to occur in the perforating arteries of lenticulostriate branched from middle cerebral artery, of thalamostriate from posterior cerebral artery and basilar artery branches and of branches from anterior choroidal artery. On MRI imaging, there are three types of lacunar infarctions; more atheromatous type, three or four high signal intensity spots are found in axial images on DWIMRI plus responsible occlusive segment of cerebral artery on MRA; intermediate type, three or four high signal intensity spots are found in axial images on DWIMRI but no occlusive segment: more lipohyalinotic type, a single high signal intensity spot is found in axial images on DWIMRI and no occlusive segment. In our case, MRI with diffusion weighted image and ADC maps showed lowering of diffusion at right posterior limb of internal capsule and corona radiata, indicating more BAD type lacunar infarction of anterior choroidal artery (9).
【Summary】
We present a seventy six-year-old woman who had lacunar infarction of branch atheromatous disease (BAD) type. It is borne in mind that in small brain arteries, occlusive mechanism of lipohyalinosis or intimal micro-atheroma can occur. The conventional lacunar infarction occurs by occlusion of a part of perforating artery due to lipohyalinosis change, while BAD type lacunar infarction occurs by total occlusion of a perforating artery. BAD type lacunar infarction expands more and the ischemic symptoms becomes worse with time rather than conventional lacunar infarction. The responsible artery to posterior limb of internal capsule and corona radiata is anterior choroidal artery.
【References】
1.Grinberg LT, et al. Vascular pathology in the aged human brain. Acta Neuropathol. 2010 Mar; 119(3): 277–290.
2.Blitstein MK, et al. MRI of cerebral microhemorrhages. AJR Am J Roentgenol. 2007;189 (3): 720-5.
3.Yousry TA, et al. Characteristic MR lesion pattern and correlation of T1 and T2 lesion volume with neurologic and neuropsychological findings in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). AJNR Am J Neuroradiol. 1999;20 (1): 91-100.
4.Auer DP, Pütz B, Gössl C et-al. Differential lesion patterns in CADASIL and sporadic subcortical arteriosclerotic encephalopathy: MR imaging study with statistical parametric group comparison. Radiology. 2001;218 (2): 443-51
5.Louis R Caplan, et al. Lacunar Infarction and Small Vessel Disease: Pathology and Pathophysiology. J Stroke. 2015 Jan; 17(1): 2–6.
6.Fisher CM. The arterial lesions underlying lacunes. Acta Neuropathol. 1968;12:1–15.
7.Fisher CM. Lacunes, small deep cerebral infarcts. Neurology. 1965;15:774–784.
8.Nakase T, et al. Clinical evaluation of lacunar infarction and branch atheromatous disease. J Stroke Cerebrovasc Dis. 2013 May;22(4):406-12.
9.Ghika JA, et al. Deep perforators from the carotid system. Template of the vascular territories. Arch Neurol 1990;47:1097–100
2019.10.2