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].

Head with branches.jpg

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

1. Di Rocco, Chieffo D, Frassanito P, Caldarelli M, Massimi L, Tamburrini G (2011) Heralding cerebellar mutism: evidence for pre-surgical language impairment as primary risk factor in posterior fossa surgery. Cerebellum 10: 551-562

2. McMillan HJ, Keene DL, Matzinger MA, Vassilyadi M, Nzau M, Ventureyra EC (2009) Brainstem compression: a predictor of postoperative cerebellar mutism. Childs Nerv Syst 25: 677-681

3. Robertson PL, Muraszko KM, Holmes EJ, Sposto R, Packer RJ, Gajjar A, Dias MS, Allen JC (2006) Incidence and severity of postoperative cerebellar mutism syndrome in children with medulloblastoma: a prospective study by the Children's Oncology Group. J Neurosurg 105: 444-451

4. Marien P, Engelborghs S, Fabbro F, & De Deyn PP (2001). The lateralized linguistic cerebellum: a review and a new hypothesis. Brain Lang 79:580-600

5. Adams and Victor's Principles of Neurology (2005)  8th edition ed. McGraw-Hill

6. Gudrunardottir T, Sehested A, Juhler M, Schmiegelow K (2011) Cerebellar mutism : Review of the literature. Childs Nerv Syst

7. Pollack IF (2001) Neurobehavioral abnormalities after posterior fossa surgery in children. Int Rev Psychiatry 302-312

8. Ammirati M, Mirzai S, Samii M (1989) Transient mutism following removal of a cerebellar tumor. A case report and review of the literature. Childs Nerv Syst 5: 12-14

9. Pollack IF, Polinko P, Albright AL, Towbin R, Fitz C (1995) Mutism and pseudobulbar symptoms after resection of posterior fossa tumors in children: incidence and pathophysiology. Neurosurgery 37: 885-893

10. Humphreys RP (1989) Mutism after posterior fossa tumor surgery. Concepts Pediatr Neurosurg 9:57–64

11. Ferrante L, Mastronardi L, Acqui M, & Fortuna A (1990) Mutism after posterior fossa surgery in children. Report of three cases. J Neurosurg 72:959-963

12. Asamoto M, Ito H, Suzuki N, Oiwa Y, Saito K, & Haraoka J (1994) Transient mutism after posterior fossa surgery. Childs Nerv Syst 10:275-278

13. Pollack IF (1997) Posterior fossa syndrome. Int Rev Neurobiol 41:411-432

14. Siffert J, Poussaint TY, Goumnerova LC, Scott RM, LaValley B, Tarbell NJ, Pomeroy SL (2000) Neurological dysfunction associated with postoperative cerebellar mutism. J Neurooncol 48: 75-81

15. Catsman-Berrevoets CE, Aarsen FK (2010) The spectrum of neurobehavioural deficits in the Posterior Fossa Syndrome in children after cerebellar tumour surgery. Cortex 46: 933-946

16. De Smet HJ, Baillieux H, Catsman-Berrevoets C, De Deyn PP, Marien P, Paquier PF (2007) Postoperative motor speech production in children with the syndrome of 'cerebellar' mutism and subsequent dysarthria: a critical review of the literature. Eur J Paediatr Neurol 11: 193-207

17. Germano A, Baldari S, Caruso G, Caffo M, Montemagno G, Cardia E, Tomasello F (1998) Reversible cerebral perfusion alterations in children with transient mutism after posterior fossa surgery. Childs Nerv Syst 14: 114-119

18. Sagiuchi T, Ishii K, Aoki Y, Kan S, Utsuki S, Tanaka R, Fujii K, Hayakawa K (2001) Bilateral crossed cerebello-cerebral diaschisis and mutism after surgery for cerebellar medulloblastoma. Ann Nucl Med 15: 157-160

19. Morris EB, Phillips NS, Laningham FH, Patay Z, Gajjar A, Wallace D, Boop F, Sanford R, Ness KK, Ogg RJ (2009) Proximal dentatothalamocortical tract involvement in posterior fossa syndrome. Brain 132: 3087-3095

20. Wells EM, Khademian ZP, Walsh KS, Vezina G, Sposto R, Keating RF, Packer RJ (2010) Postoperative cerebellar mutism syndrome following treatment of medulloblastoma: neuroradiographic features and origin. J Neurosurg Pediatr 5: 329-334

21. Wells EM, Walsh KS, Khademian ZP, Keating RF, Packer RJ (2008) The cerebellar mutism syndrome and its relation to cerebellar cognitive function and the cerebellar cognitive affective disorder. Dev Disabil Res Rev 14: 221-228

22. Avula S, Mallucci C, Kumar R, Pizer B (2015) Posterior fossa syndrome following brain tumour resection: review of pathophysiology and a new hypothesis on its pathogenesis. Childs Nerv Syst Oct;31(10):1859-67