PATHOPHYSIOLOGY
Pre-operative symptoms
The pre-operative symptoms of post-operative pediatric CMS may be caused by brainstem compression/infiltration by the tumor, with affection of the DTC-pathway [1, 2, 3] and secondary supratentorial hypoperfusion [4]. Although not specified in the literature, local compressive forces and edema of the cerebellum itself are probably also important. Somatic symptoms such as headache and vomiting are, on the other hand, caused by increased intracranial pressure [5].
Post-operative symptoms
The delayed onset and resolution of post-operative symptoms of post-operative pediatric CMS are characteristic and well-described, but the pathophysiological mechanisms involved are not fully understood. Surgical manipulation and traction along ascending fiber systems (including the DTC-pathway) are considered by many to be primary pathogenic factors [6], while secondary process initiated by the tumor resection seem play a role in the delayed onset of symptoms [7]. These may involve edema (swelling) of the cerebellum, superior peduncles and brainstem [8, 9], hypoperfusion (due to surgical manipulation/coagulation/vasospasms) and subsequent ischemia (inadequate blood supply) of the cerebellum [10, 11, 12, 13], transient dysregulation of neurotransmitter release [14], crossed cerebello-cerebral diaschisis (see under Anatomy) [15, 16, 17, 18], axonal injury [19] and thermal injury related to the use of ultrasonic aspirators [22] . Many post-operative pediatric CMS patients have been been shown to develop lasting atrophy (waisting/decrease in size) of the vermis and cerebellar hemispheres [18, 20] as well as signs of damage to the DTC-pathway, and there has been increasing evidence of permanent cortical dysfunction as a result of damage to these outflow tracts [20, 21].
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Definitions, Incidence, Symptoms, Anatomy, Imaging findings, Risk factors, Prognosis, Treatment, Prevention
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