====== Traumatic posterior fossa subdural hematoma ======

[[Posterior fossa subdural hematoma]] cases account for approximately 0.2%
((Pal, D; Gnanalingham, K; Peterson, D; A case of spontaneous acute subdural
haematoma in the posterior fossa following anticoagulation.))
of all [[head trauma]]s and 0.3-3%
((Borzone M, Rivano C, Altomonte M, Baldini M. Acute traumaticposterior fossa
subdural haematomas. Acta Neurochir (Wien). 1995;135:32–37.))
((Hec´imovic´ I, Blagus G, Kristek B, Rukovanjski M, Vrankovic´ D. Successful
treatment of traumatic acute posterior fossa subdural hematoma: report of two
cases. Surg Neurol. 1999; 51:247–251.))
of the [[traumatic subdural hematoma]]s. 

Rarely, [[subdural hematoma]]s may be spontaneous, with no previous trauma.
These cases are usually secondary to bleeding from an underlying pathology such as [[arteriovenous malformation]] (AVM), [[tumor]] or coagulation dysfunction
((Stendel R, Schulte T, Pietilä A, Suess O, Brock M. Spontaneous bilateral
chronic subdural haematoma of the posterior fossa. Case report and review of
the literature. Acta Neurochir(Wien) 2002;144:497–500.))
((M. Berhouma, S. Houissa, H. Jemel, M. Khaldi. Spontaneous chronic subdural
hematoma of the posterior fossa. Journal of Neuroradiology. 2007;))
According to the medical literature, only five cases of acute spontaneous subdural hematomas in the
posterior fossa were reported
((Pal, D; Gnanalingham, K; Peterson, D; A case of spontaneous acute subdural
haematoma in the posterior fossa following anticoagulation.))
((McClelland, R.R; Ramirez-Lassepas, M. Posterior fossa subdural hematoma
demonstrated by vertebral angiography. Neurorradiology 1976. 10,181-185.)).

The low rate of occurrence of this type of hematoma in the posterior fossa could be explained by the few number of bridging veins in this region and the uncommon direct damage to the occipital dural sinus
((Hec´imovic´ I, Blagus G, Kristek B, Rukovanjski M, Vrankovic´ D. Successful
treatment of traumatic acute posterior fossa subdural hematoma: report of two
cases. Surg Neurol. 1999; 51:247–251.))
((Stendel R, Schulte T, Pietilä A, Suess O, Brock M. Spontaneous bilateral
chronic subdural haematoma of the posterior fossa. Case report and review of
the literature. Acta Neurochir(Wien) 2002;144:497–500.)).

Moreover, Goldsmith and Plunkett hypothesize that since the [[posterior fossa]] space is almost completely fulfilled by the [[brainstem]] and [[cerebellum]], the movement of the [[skull base]] is synchronic to those structures, therefore no shear forces occur in this compartment
((Goldsmith, W; Plunkett, J. A Biomechanical Analysis of the Causes of
Traumatic Brain Injury in Infants and Children. The American Journal of
Forensic Medicine and Pathology. 25:2.2004 )).

===== Case series =====

Ten patients with traumatic posterior fossa SDHs were admitted to our hospital. There were seven males and three females, with an age range of 3 years to 97 years (mean, 57.5 years). Coagulopathies were observed in five patients. The causes of injury were motor vehicle crash in three patients, falls in six patients, and being hit by an iron plate in one patient. The mean admission Glasgow Coma Scale score was 8.3. Skull fractures were revealed in six patients. Hematoma sizes ranged from 5 mm to 20 mm (mean, 7.7 mm). Two patients presented with isolated posterior fossa SDHs, and eight patients presented with associated intracranial lesions. Only one patient was treated surgically for posterior fossa SDHs associated with intracerebellar hematomas. The poor outcome rate was 90% and the mortality was 50%.

A review of the literature revealed the following characteristics of posterior fossa SDHs: (1) a relatively high frequency of occipital impacts and fractures, (2) a low Glasgow Coma Scale score, (3) a high frequency of associated intracranial lesions, especially supratentorial lesions and intracerebellar hematomas, (4) a potential for lesion evolution, especially within 2 days, and (5) a high poor outcome rate and mortality
((Takeuchi S, Takasato Y, Wada K, Nawashiro H, Otani N, Masaoka H, Hayakawa T.
Traumatic posterior fossa subdural hematomas. J Trauma Acute Care Surg. 2012
Feb;72(2):480-6. doi: 10.1097/TA.0b013e31823c89b3. PubMed PMID: 22327987.)).