Lacunar Syndromes

http://en.wikipedia.org/wiki/Lacunar_stroke

Charles Miller Fisher cadaver dissections 1965 publication in Neurology
200-800 micrometer penetrating arteries (?ref)
25% of all ischemic (?ref)
Location (?ref)

1. Putamen 37%
2. Thalamus 14%
3. Caudate 10%
4. Pons 16%
5. Capsule posterior limb 10%

The two proposed mechanisms are microatheroma and lipohyalinosis. At the beginning, lipohyalinosis was thought to be the main small vessel pathology, but microatheroma now is thought to be the most common mechanism of arterial occlusion (or stenosis). 

Each of the 5 classical lacunar syndromes has a relatively distinct symptom complex. Symptoms may occur suddenly, progressively, or in a fluctuating (e.g., the capsular warning syndrome) manner. Occasionally, cortical infarcts and intracranial hemorrhages can mimic lacunar infarcts, but true cortical infarct signs (such as aphasia, neglect, and visual field defects) are always absent.

Name	Location of infarct	Presentation
Pure motor stroke/hemiparesis (most common lacunar syndrome: 33-50%)	posterior limb of the internal capsule,basis pontis, corona radiata	It is marked by hemiparesis or hemiplegia that typically affects the face, arm, or leg of one side. Dysarthria, dysphagia, and transient sensory symptoms may also be present.
Ataxic hemiparesis (second most frequent lacunar syndrome)	posterior limb of the internal capsule,basis pontis, and corona radiata, red nucleus, lentiform nucleus, SCA infarcts, ACA infarcts	It displays a combination of cerebellar and motor symptoms, including weakness and clumsiness, on the ipsilateral side of the body. It usually affects the leg more than it does the arm; hence, it is known also as homolateral ataxia and crural paresis. The onset of symptoms is often over hours or days.
Dysarthria/clumsy hand (sometimes considered a variant of ataxic hemiparesis, but usually still is classified as a separate lacunar syndrome)	basis pontis, anterior limb or genu of internal capsule, corona radiata, basal ganglia, thalamus, cerebral peduncle	The main symptoms are dysarthria and clumsiness (i.e., weakness) of the hand, which often are most prominent when the patient is writing.
Pure sensory stroke	contralateral thalamus (VPL), internal capsule, corona radiata, midbrain	Marked by persistent or transient numbness, tingling, pain, burning, or another unpleasant sensation on one side of the body.
Mixed sensorimotor stroke	thalamus and adjacent posteriorinternal capsule, lateral pons	This lacunar syndrome involves hemiparesis or hemiplegia with ipsilateral sensory impairment

http://stroke.ahajournals.org/content/38/10/2706.full

The pathophysiological heterogeneity of ischemic stroke may be relevant to the development of acute-phase therapies because it is possible that what works for one subtype of stroke may work differently for another. Although no clinical stroke syndrome is absolutely pure with respect to pathophysiology, lacunar syndromes are the most homogeneous. Lacunar syndromes are usually due to a small subcortical infarct in the territory of a penetrating artery caused by in situ microatheroma or lipohyalinosis. Neurochemical studies suggest that subcortical ischemia may respond differently to hyperacute intervention than cortical ischemia. Subgroup analyses in a trial of a putative neuroprotective agent suggested the possibility of (an unexpected) benefit in patients with lacunar strokes. (Images Trial)