![]() 308 The contralateral PICA infarct is usually small and limited within the medial PICA territory ( Fig. Among them, the first one seems to be the most frequent mechanism. Several hypotheses have been put forth to explain the pathogenesis: 305–307 (1) unilateral supply to both medial PICA territories, (2) both PICAs arising from an occluded BA, (3) pressure effect is caused by a large PICA infarct, (4) hemodynamic mechanism with hypoperfusion in the most peripheral branches, and (5) double, simultaneous embolic strokes. Occasionally, PICA territory cerebellar infarctions occur bilaterally ( Fig. While infarcts limited to a branch territory almost never become edematous, progressive herniation occasionally occurs in patients with whole PICA territory infarction ( Fig. The clinical manifestation of whole PICA territory infarction is the combination of medial and lateral PICA infarction. Unlike SCA territory infarcts, dysarthria is absent or mild in these patients. Compared with medial PICA infarction, lateral PICA territory infarctions rarely produce acute rotatory vertigo and lateropulsion, 304 and are less often associated with LMI. In patients with lateral PICA territory cerebellar infarction, the most common symptom at onset is acute unsteadiness, gait ataxia, and unilateral limb ataxia ( Fig. However, head impulse and bithermal caloric tests were normal, which may distinguish this condition from peripheral vestibulopathy. In a series describing small infracts limited to the nodule, 303 all patients presented with isolated vertigo, unilateral ipsilesional nystagmus and falling to the opposite direction. This area corresponds to the vestibular portion of the cerebellum and is exclusively supplied by medial PICA. These patients usually have medial and caudal cerebellar infarction involving the uvulonodular complex of the vermis. 289,299 The isolated acute vertigo from PICA territory infarction mimicks labyrinthitis 300–302 the vertigo may be aggravated (or relieved) on certain head positions and patients may describe recurrent vertigo symptoms. Medial PICA infarctions ( Figs 26-11, 26-12) present with isolated vertigo, with or without axial lateropulsion and dysmetria. In one series, 296 medial PICA infarctions (n = 23) outnumbered lateral PICA (n = 9) or whole PICA (n = 9) infarctions. PICA territory infarction can affect the full territory, but partial (medial or lateral) territory involvement is more common, occurring in two-thirds 298 to three-quarters 284 of PICA cerebellar infarctions. 287 A patient's attempts to stand or walk are usually associated with falling to one or either side. Another striking finding in PICA territory infarction is axial lateropulsion, a phenomenon suggestive of a lateral displacement in the representation of the center of gravity. 284 nystagmus was common (75%) and was either horizontal (ipsilateral in 47% of patients, contralateral in 5%, bilateral in 11%) or vertical (11% of patients). 284 Headache is usually unilateral, occurring in cervical, occipital, or both regions. Manifestations of PICA territory infarction include vertigo, headache, gait ataxia, limb ataxia, and nystagmus. Although much less common, MMI may occur together with PICA cerebellar infarction, 296 supporting the latter argument. However, it is also possible that ICVA atherothrombosis simultaneously occludes both the PICA and medullary perforators. The co-occurrence of the LMI is usually due to involvement of medullary perforators in the presence of proximal PICA occlusion. In patients with partial LMI syndromes, ipsilateral trigeminal sensory loss is more common than other components or may be an early sign heralding more extensive LMI symptoms, probably because the descending trigeminal tracts are located in the dorsal medullary area primarily supplied by the PICA ( Fig. However, medullary lesions may not be seen or detected only after repeated MRI scans. In these patients, MRI usually shows concomitant involvement of the medulla ( Fig. The syndromes can be either complete or partial. The symptoms of LMI concomitantly occur in approximately 10% 296 to 33% 284 of the patients with PICA infarction. However, PICA infarctions are probably underdiagnosed because they occasionally present with isolated vertigo mimicking peripheral vestibulopathy. 296 PICA infarction accounts for 2% of all ischemic strokes. ![]() PICA territory infarction is more frequent than SCA territory infarction. ![]() Caplan, in Stroke (Sixth Edition), 2016 Clinical-topographic Correlation Posterior Inferior Cerebellar Artery Infarction. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |