Figure 1
Non-contrast CT head
A fluid attenuation subdural collection is seen along the right fronto-temporal cerebral convexity. It appears of relatively highter attenuation as compared to the intraventricular CSF.
Posttraumatic subdural hygroma
SectionNeuroradiology
Case TypeClinical Cases
AuthorsArora A, Mukund A, Thapar S, Jain D
Connected authors
30 years, male
Clinical History
A 30-year-old male patient met with a road-traffic accident and sustained major abdominal injuries for which he underwent exploratory laporotomy. His cranium was imaged on day 7 after the injury, as he complained of mild headache. There was no neurological deficit on clinical evaluation.
Imaging Findings
Non-contrast CT head revealed fluid-attenuation subdural collection (hygroma) along the right frontal cerebral convexity. This displayed relatively higher attenuation (15-18 H.U) as compared to the intraventricular CSF (2-5 H.U). There was suggestion of another possible very thin subdural hygroma along left frontal convexity extending into the inter-hemispheric fissure (Fig. 4).
Discussion
Post traumatic subdural hygroma refers to cerebrospinal fluid accumulation in the subdural space subsequent to closed head injury [1-5]. It is a relatively common complication of blunt head trauma with a reported incidence of 5–20% in all closed head injury patients. In spite of its frequent occurrence its pathogenesis, natural history and clinical significance remain unclear [2]. The separation of the dura-arachnoid interface has been implicated as the causative factor along with impaired CSF absorption [2-4].
Subdural hygroma is conventionally considered as a delayed traumatic lesion, however, it can be discovered as early as within first few hours of trauma. The exact etiopathogenesis is poorly understood, however, the most acknowledged mechanism suggests traumatic arachnoid tear with efflux and entrapment of CSF in the subdural space (flap valve mechanism). Another probable mechanism suggests that the subdural fluid collection is more likely to be an effusion (serum fluid) from traumatized vessels than CSF collection. Although there are no dynamics studies confirming or refuting the flap valve theory, it is still the most accepted [3].
Most posttraumatic hygromas remain clinically silent as they do not produce significant mass effect; although, a few cases may show gradual deterioration during the chronic stage. Accordingly, traumatic hygromas are chiefly managed conservatively as their sizes mostly diminish spontaneously. Very rarely, they may be large enough to cause cause mass effect which may require surgical decompression. The overall prognosis is determined by the severity of the primary head injury and not upon the hygroma per se [2].
At imaging, they present from the onset as hypodense subdural fluid collections on CT examinations [1]. Differential diagnosis has to be made with subdural haematoma of chronic chronology, and cerebral atrophy with enlargement of the subarachnoid space (especially in the elderly population). CT density modifications changing into chronic subdural haematoma has been reported in the literature, in as many as 0-58 % cases of traumatic subdural hygroma [4].
Subdural hygroma is conventionally considered as a delayed traumatic lesion, however, it can be discovered as early as within first few hours of trauma. The exact etiopathogenesis is poorly understood, however, the most acknowledged mechanism suggests traumatic arachnoid tear with efflux and entrapment of CSF in the subdural space (flap valve mechanism). Another probable mechanism suggests that the subdural fluid collection is more likely to be an effusion (serum fluid) from traumatized vessels than CSF collection. Although there are no dynamics studies confirming or refuting the flap valve theory, it is still the most accepted [3].
Most posttraumatic hygromas remain clinically silent as they do not produce significant mass effect; although, a few cases may show gradual deterioration during the chronic stage. Accordingly, traumatic hygromas are chiefly managed conservatively as their sizes mostly diminish spontaneously. Very rarely, they may be large enough to cause cause mass effect which may require surgical decompression. The overall prognosis is determined by the severity of the primary head injury and not upon the hygroma per se [2].
At imaging, they present from the onset as hypodense subdural fluid collections on CT examinations [1]. Differential diagnosis has to be made with subdural haematoma of chronic chronology, and cerebral atrophy with enlargement of the subarachnoid space (especially in the elderly population). CT density modifications changing into chronic subdural haematoma has been reported in the literature, in as many as 0-58 % cases of traumatic subdural hygroma [4].
Differential Diagnosis List
Posttraumatic subdural hygroma
Chronic subdural bleed
Cerebral atrophy
Final Diagnosis
Posttraumatic subdural hygroma
References
[1] Deltour P, Lemmerling M, Bauters W, Siau B, Kunnen M (1999) Posttraumatic subdural hygroma: CT findings and differential diagnosis. JBR-BTR 82:155-6 (PMID: 10555420)
[2] Lee KS (1998) The pathogenesis and clinical significance of traumatic subdural hygroma. Brain Inj 12:595-603 (PMID: 9653522)
[3] Zanini MA, de Lima Resende LA, de Souza Faleiros AT, Gabarra RC (2008) Traumatic subdural hygromas: proposed pathogenesis based classification. J Trauma 64:705-13 (PMID: 18332811)
[4] Zanini MA, Resende LA, Freitas CC, Yamashita S (2007) Traumatic subdural hygroma: five cases with changed density and spontaneous resolution. Arq Neuropsiquiatr 65:68-72 (PMID: 17420830)
[5] Kamezaki T, Yanaka K, Fujita K, Nakamura K, Nagatomo Y, Nose T (2004) Traumatic acute subdural hygroma mimicking acute subdural hematoma. J Clin Neurosci 11:311-3 (PMID: 14975427)
Case information
| URL: | https://www.eurorad.org/case/9550 |
| DOI: | 10.1594/EURORAD/CASE.9550 |
| ISSN: | 1563-4086 |
Figure 2
Non-contrast CT head
NCCT reveals right frontal cerebral convexity subdural hygroma.
Figure 3
Non-contrast CT head
Right frontal cerebral convexity subdural collection is seen with subtle prominence of the contralateral CSF space.
Figure 4
Non-contrast CT head
Right frontal subdural hygroma is well visualised. There is suggestion of a small left subdural hygroma on these higher cuts as well.
Non-contrast CT head
A fluid attenuation subdural collection is seen along the right fronto-temporal cerebral convexity. It appears of relatively highter attenuation as compared to the intraventricular CSF.
Ankur Arora, ILBS Hospital, New Delhi, India.
Ankur Arora, ILBS Hospital, New Delhi, India.
Non-contrast CT head
NCCT reveals right frontal cerebral convexity subdural hygroma.
Ankur Arora, ILBS Hospital, New Delhi, India.
Ankur Arora, ILBS Hospital, New Delhi, India.
Non-contrast CT head
Right frontal cerebral convexity subdural collection is seen with subtle prominence of the contralateral CSF space.
Ankur Arora, ILBS Hospital, New Delhi, India.
Ankur Arora, ILBS Hospital, New Delhi, India.
Non-contrast CT head
Right frontal subdural hygroma is well visualised. There is suggestion of a small left subdural hygroma on these higher cuts as well.
Ankur Arora, ILBS Hospital, New Delhi, India.
Ankur Arora, ILBS Hospital, New Delhi, India.