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Tetraventricular Hydrocephalus And Subarachnoid Fat Vesicles Induced By Ruptured Spinal Dermoid Cyst

 Mustapha Maâroufi*, Imane Kamaoui*, Mohammed Benzagmout**, Saďd Boujraf***, Siham Tizniti*

*Department of Radiology, University Hospital Hassan II, Fez , Morocco .
Department of Neurosurgery, University Hospital Hassan II, Fez , Morocco .
***Department of Biophysics and Clinical MRI Methods, Faculty of Medicine and Pharmacy, University of Fez , Morocco .

Address for Correspondence:

Associate Prof. Saďd Boujraf
Department of Biophysics and Clinical MRI Methods
Faculty of Medicine and Pharmacy, University of Fez
BP. 1893; Km 2.200, Sidi Hrazem Road, Fez 30000 , Morocco
Phone: 00 212 67 780 442, Fax: 00 212 35 619 321



The authors report a case of spinal dermoid cyst which ruptured; this originated a migration of free fat vesicles into the ventricles and subarachnoidal spaces. The fat vesicles caused obstructive hydrocephalus; witch represents a quite exceptional complication. The intracranial fat causing hydrocephalus was found before the discovery of the spinal mass. The authors suggest that the finding of intracranial fat in the absence of a local source makes the search for an intraspinal dermoid cyst.

J.Orthopaedics 2007;4(4)e23

dermoid, rupture, free fat, hydrocephalus, MR imaging.

Free fat in the brain’s cerebrospinal fluid (CSF) is recognized as complication of ruptured intracranial dermoid tumors. On the contrary, the diffusion of fat drops in intracranial CSF from spinal dermoid cysts is unusual.

We report a case of spinal dermoid cyst without associated spinal dysraphism originating subarachnoidal, cisternal and intraventricular fat drops. The fat deposits caused obstructive hydrocephalus. In our case the finding of intracranial fat and obstructive hydrocephalus preceded the discovery of the spinal neoplasm.

Case report

A 35-year-old man, with a 1-year history of headaches, seizures and a decrease of the general mental status. At the clinical examination there was hyperreflexia of lower extremities. No history of spinal trauma or lumbar puncture was registered. Cerebral magnetic resonance imaging (MRI) showed an obstructive hydrocephalus with enlarged aqueduct due to fat drops that probably obstructed the caudal portion of aqueduct, there was another fat deposits located cisterna magna, cerebellopontine, interpeduncular, and other basal cisterns (Figure 1). In the absence of a local source of intracranial fat drops we performed spinal MRI which revealed a large mass at the conus medullarus, which was constituted of two portions: a cranial one, that was tissular, isointense with the spinal cord on T1-weighted images; and a caudal one that was fatty, showing higher signal on T1 and T2 weighted images. Small subarachnoid fat deposits are present at T7 and T9 level (Figure 2), linear high-signal area within the distal spinal cord might represent syringomyelia, edema or pericystic gliosis. On lumbar puncture, CSF protein and cells were in a normal range. The patient underwent radical removal of the spinal dermoid cyst of the conus medullarus, histologically identified as a dermoid cyst. 

Discussion :

Spinal dermoid are rare benign congenital lesions (1-2% of all intraspinal tumors) originating from inclusions of epithelial elements within the neural groove at the time of its closure to form the neural tube between the third and fifth weeks of embryonic life [1]. About 25% are found in the sacrococcygeal region [2]. They may occur within the spinal cord.

The clinical history is related to the lesion site, their slow rate of growth allows reaching a considerable size even without causing any symptoms.

 Unless insidious rupture occurs; the spillage of the keratin and cholesterol products breakdown can generate variable symptoms such as headache, dementia, seizures or transient cerebral ischemia [3, 4]. Chemically induced meningitis follows dermoid rupture with variable clinical sequela. Symptoms of our patient can be explained by the meningeal irritation by the spilled cholesterin materiel.

MRI is the modality of choice for diagnosing the dermoid tumors; it shows different components of a dermoid cyst, as well as small free fat droplets in the subarachnoidal space. Dermoid cysts usually present relatively homogeneous signal, higher than the spinal cord on T1-weighted images. However, in some cases a more heterogeneous pattern is observed, related to the composition of the tumor. The relatively high signal from fat on MRI, especially the bright signal on T1 weighting, makes for easy identification of lipid droplets, particulary within the cerebral sulci, fissures and the perimedullary subarachnoid space. Fat droplets are rarely recognized on CT because of their small size and their similar density to CSF on routine windowing. The differential diagnosis of dermoid cysts on imaging includes lesions with high lipid content such as teratomas and lipomas.

Intracranial fat spread originated from intraspinal dermoid rupture has been recently emphasized [5, 6]. Our case is a further demonstration of this possibility; witch indicates the interest of complementary brain imaging examination of patients with intraspinal dermoid, and vice-versa.

In addition to generalized subarachnoid and ventricular spread of droplets fat, our patient developed obstructive triventricular hydrocephalus witch is an unusual manifestation [7]. The hydrocephalus may be attributed to early alteration of cerebrospinal fluid circulation by fatty materiel in the caudal portion of cerebral aqueduct, and subsequent block by subarachnoid fibrosis explaining the narrowing of this portion [8, 9] (Figure 1).




Figure 1: Axial and sagittal spin-echo T1-weighted image. Lipid droplets are present in the cisterna magna, 3rd ventricle, interhemicerebral fissure and schismatic cistern. A small droplet is seen in the caudal portion of the cerebral aqueduct (arrow). The cranial portion of witch is enlarged


Figure 2: Sagittal spin-echo T1 and T2-weighted images. An exophytic intramedullary dermoid tumor is seen in the lumbar enlargement. The cyst has a cranial portion that is solid and isointense with the spinal cord (arrow) and a caudal portion giving high signal (arrowhead). Two small lipid droplets are seen in the posterior subarachnoid space at T7 and T9. Linear high-signal area within the distal spinal cord may represent syringomyelia, edema or pericystic gliosis

Reference :

1. Messori A, Polanara G, Serio A,Gambelli E, Salvolini U. Expanding experience with spontaneous dermoid rupture in the MRI era: diagnosis and follow-up. European Journal ol Radiology 2002;43:19-27

2. Kavita K, Pankaj A, Sunil I. Dermoid of the conus medullaris. Journal of clinical neuroscience 2004;11(7):796-797

3. Karabulut N, Oguzkurt L. Tetraventricular hydrocephalusdue to ruptured intracranial dermoid cyst. Europeen Radiology 2000;10:1810-1811        

4. Lunardi P, Missori P, Rizzo A, Gagliardi FM. Chemical meningitis in ruptured intracranial dermoid. Case report and review of the litterature. Surgical neurology 1989;32:449-452

5. Barsi P, Kenez J, Varallyay G, Gergely L. Unusual origin of free subarachnoid fat drops: a ruptured spinal dermoid tumour.Neuroradiology 1992;34:343–344.

6. Calabro` F, Capellini C, Jinkins JR. Rupture of spinal dermoid tumors with spread of fatty droplets in the cerebrospinal fluid pathways. Neuroradiology 2000;42:572–579.

7. Cavazzani P, Ruella A, Michelozzi G, Andrioli G. Spinal dermoid cyst originating intracranial fat drops causing obstructive hydrocephalus: case reports. Surg Neurol 1995;43:466–469.

8. Scearce TA, Shaw CM, Bronstein AD, Swanson PD. Intraventricular fat from a ruptured sacral dermoid cyst: clinical, radiographic, and pathological correlation. Case report. J Neurosurg 1993;78:666–668.

9. Roeder MB, Bazan C, Jinkins JR. Ruptured spinal dermoid cyst with chemical arachnoiditis and disseminated intracranial lipid droplets. Neuroradiology 1995;37:146–147.


This is a peer reviewed paper 

Please cite as : Mustapha Maâroufi : Tetraventricular Hydrocephalus And Subarachnoid Fat Vesicles Induced By Ruptured Spinal Dermoid Cyst  

J.Orthopaedics 2007;4(4)e23





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