Intracranial arachnoid cysts: radiological study of the incidental, the symptomatic and the complicated.

Transcription

1 Intracranial arachnoid cysts: radiological study of the incidental, the symptomatic and the complicated. Poster No.: C-1092 Congress: ECR 2015 Type: Educational Exhibit Authors: C. Ospina Moreno, I. Montejo Gañán, A. C. Vela Marin, A. Castan, M. A. Marin, J. Gonzalez, C. Sebastián, D. Marquina, M. Cozar Bartos; Zaragoza/ES Keywords: Cysts, Cerebrospinal fluid, Diagnostic procedure, MR, CT, Neuroradiology brain DOI: /ecr2015/C-1092 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 21

2 Learning objectives To assess the main radiological features of intracranial arachnoid cyst. To know the clinical presentation, evolution and complications that are associated with the arachnoid cyst. Background Arachnoid cysts (AC) are benign lesions that are formed between the inner and outer layers of the arachnoid. They are #lled with clear cerebral spinal fluid (CSF) and they do not have direct communication with the ventricular system. The origin of these cysts is thought to be congenital by dysgenesis in embryological development of subarachnoid space. Other causes have also been attributed to trauma, mastoiditis, meningitis, and subarachnoid hemorrhage. AC account for 1% of all intracranial space occupying lesions. The size varies, from small and incidental to a large lesions that cause raised intracranial pressure and / or direct compression of cranial structures. The most common associated symptoms include headache, epilepsy, motor and sensory disorders and endocrine disorders. They can cause bone remodeling and macrocrania. About 25% of cases are found incidentally on CT and MRI of asymptomatic patients. The incidence is higher in men than in women. Most are detected in less than 16 years. In its evolution over time can increase in size, decrease or remain stable. Cases of spontaneous resolution have been reported, some of them after a head injury. Two thirds of the AC are located in the supratentorial space, half of which are in the middle cranial fossa. Other locations include the suprasellar region, convexity, interhemispheric, and intraventricular. The remaining third are located in the posterior fossa. Fig. 1 on page 3 In 1980 Galassi et al classified arachnoid cysts of middle cranial fossa into three types according to their size and effect on neighboring structures. Page 2 of 21

3 Fig. 2: Galassi classification References: Zaragoza, Hospital Universitario Miguel Servet - Zaragoza/ES Type I: small size, located in the anterior temporal lobe. No mass effect Type II: medium-size, located in the anterior and middle temporal fossa. Temporal lobe displaced. Type III: constitutes a large oval or round cyst that fills the entire temporal fossa. Large mass effect. Images for this section: Page 3 of 21

4 Fig. 1: T2-weighted MR images show different locations of arachnoid cysts. A) Right temporal fossa. B) Right frontal lobe C) Right cerebellopontine angle. D and E) Right cerebellar hemisphere. F) Left choroidal fissure. Page 4 of 21

5 Fig. 2: Galassi classification Page 5 of 21

6 Findings and procedure details RADIOLOGICAL DIAGNOSIS: Computed tomography (CT) is the gold standard for diagnosis. CT imaging of an AC will show a noncalcified homogeneous extra-axial cystic lesion, similar to LCR attenuation that does not enhance with contrast administration and produces remodeling of adjacent bone structures. MRI is a useful tool for diagnostic complementation. On MRI AC has the same signal intensity as CSF at all sequences. AC will suppress completely on fluid attenuated inversion recovery (FLAIR) imaging and will not demonstrate restriction on diffusionweighted images, therefore are hypointense on these sequences Fig. 3 on page 7 Intracystic bleeding or high concentrations of proteins may change the signal intensity. AC displace adjacent nerves and cranial vessels rather than engulf them. The use of phase-contrast (PC) cine MR imaging allows for observation of the CSF flow between the subarachnoid space to the interior of the cyst. On the PC cine MRI to observe hyperitense or hypointense areas within the AC means that the cyst and the subarachnoid space are communicated. Differentiation of communicating cysts and noncommunicating ones can be useful for surgical planning. CLINICAL MANIFESTATIONS The clinical manifestations will depend on the size of the cyst and its location Fig. 4 on page 8. Small cysts are often incidental findings Fig. 5 on page 9, while large cysts are usually symptomatic. When they are too large can cause raised intracranial pressure and / or direct compression of cranial structures. They can cause bone remodeling, in young children may produce macrocrania and / or cranial asymmetry Fig. 6 on page 10. The AC have also been associated with delayed psychomotor development. In older children the predominant symptom is headache Fig. 7 on page 11, and up to 25% of cases may be associated with seizures Fig. 8 on page 12 Cysts in the chiasmatic region can produce visual disturbances and endocrine disorders due to compromise of the hypothalamus-pituitary. Fig. 9 on page 13. The AC can Page 6 of 21

7 produce hydrocephalus by compression of the third ventricle and the fourth ventricle when they are located in the posterior fossa. COMPLICATIONS: Complications are rare but potentially serious, among these include subdural hematoma Fig. 10 on page 14, intracystic hemorrhage, acute cyst expansion and subdural hygroma Fig. 11 on page 15, Fig. 12 on page 16 and Fig. 13 on page 17. DIFFERENTIAL DIAGNOSIS The main differential diagnosis will do with epidermoid cysts, which look identical to CSF on CT and MRI, but epidermoids cysts do not supress completely on FLAIR sequences and they restrict on diffusion -weighted images. Fig. 14 on page 18 TREATMENT Surgical treatment, either by craniotomy, endoscopic fenestration, needle aspiration or cystoperitoneal shunting Fig. 15 on page 19 is reserved for cases of large cysts, symptomatic or complicated. Expectant management is recommended for patients with small and asymptomatic cysts. Images for this section: Page 7 of 21

8 Fig. 3: A 12 year old boy who was admitted in our hospital with diplopia. The CT scan shows AC of the right temporal fossa. The cyst has the same signal intensity as CSF at all MRI sequences and does not enhance with contrast administration. It produces a discrete mass effect on frontal lobe and the right temporal lobe is hypoplastic. Right middle cerebral artery is slightly displaced by the cyst. Page 8 of 21

9 Fig. 4: A and B): Coronal FIESTA (Fast Imaging employing steady-state acquisition) images, show an arachnoid cyst in the right cerebellopontine angle with mass effect and brainstem displacement to the left side. There are displacement vessels and left cranial nerves VII-VIII (arrow), which may explain the symptoms. The right cranial nerve VIII is also somewhat compressed. C) Transverse diffusion-weighted MR image shows no restriction. Page 9 of 21

10 Fig. 5: Small arachnoid cyst located in the left choroid fissure, this is an incidental finding in an 8 year old boy who was studied by headache. Page 10 of 21

11 Fig. 6: A 3 year old boy with bulging of the right temporal bone. MRI shows AC in the middle cranial fossa with right temporal lobe atrophy. The cyst produces bone remodeling of the temporal fosse, with temporal bone prominence (arrowheads). Also note the solid lesion in the suprasellar cistern that does not enhance with contrast (arrow) is a hypothalamic hamartoma as a concomitant finding. Page 11 of 21

12 Fig. 7: A 16 year old male patient with headache refractory to treatment, so he underwent surgery A y B) AC in the right frontal convexity. C) Postoperative MRI, shows the cyst volume decrease. Page 12 of 21

13 Fig. 8: A 6 year old boy with seizure disorder. A and B)CT scan shows an AC in the right temporal fossa, bone remodeling is observed with enlargement of the temporal fossa. D and E) T1WI MRI and FLAIR sequence, important temporal lobe atrophy is observed. C and F) T2WI MRI and SPGRT1 sequence, show the middle cerebral artery displaced by the cyst. Page 13 of 21

14 Fig. 9: MR imaging of a 32-year-old female with intrasellar arachnoid cyst associated with hyperprolactinemia and infertility. Page 14 of 21

15 Fig. 10: A 42 year old male with persistent headache of fifteen days. A) and B) CT scan shows subacute subdural hematoma right which is isodense to gray matter, moderate mass effect is observed. C) Sagittal T1WI MRI, demonstrating hyperintese subdural haematoma, arachnoid cyst and intracystic hemorrhage in the temporal fosse. D y E) Axial FLAIR secuence MRI, shows the presence of subdural haematoma in the right frontotemporal region and the cyst in the temporal fosse. The subdural collection has blood at different stages of evolution, corresponding with subacute hematoma. F)Postoperative axial CT scan, demonstrates the arachnoid cyst in the right temporal lobe. Page 15 of 21

16 Fig. 11: A 16-year-old boy who presented a 30-day history of gradually worsening headache. CT scan and MRI show arachnoid cyst in the left middle temporal fossa with involvement of the choroid fissure, the cyst presents signs of rupture and bilateral subdural hygroma. Also presents mild mass effect on the left hemisphere and ventricular system. Page 16 of 21

17 Fig. 12: A, B and C Postoperative MRI at 4 months from patient of figure 11. D, F and E initial imaging. The arachnoid cyst in the right temporal lobe is smaller than the initial imaging (arrow). The subdural hygromas have disappeared. B and C) MRI shows a septum pellucidum cyst (asterisk) that was not observed in the initial study due to mass effect on the lateral ventricles. Page 17 of 21

18 Fig. 13: A 3-year-old boy was seen in our hospital because of headache, vomiting and drowsiness. He had a head injury a month ago. A-E) MR imaging and CT scan show bilateral hygromas (arrows) and a large arachnoid cyst in the left temporal fossa which produces minimal displacement of the optic chiasm (arrowhead). A mega cisterna magna as normal variant is observed (asterisk). He underwent surgery with placement of a cystoperitoneal shunt. F) Control TC scan two years later, disappearance of AC is observed. After the ruptue, these cysts may decrease in size and even disappear. Page 18 of 21

19 Fig. 14: MR imaging of an epidermoid cyst in the posterior fossa, the cyst is isointense to CSF on both T1 and T2-weighted MR images. It do not suppress completely on FLAIR images and restrict (show high signal intensity) on diffusion-weighted images. Page 19 of 21

20 Fig. 15: A 59 years old female with large AC occupying the temporal fossa with a great mass effect. She underwent surgery with parietal burr hole and placement of a cystoperitoneal shunt. Page 20 of 21

21 Conclusion Most arachnoid cysts remain asyntomatic. Nevertheless, they may have symptoms and complications. Therefore it is necessary to know well their typical and atypical sites, as well as the symptoms and complications depending on their size and location. Personal information References Yildiz H, Erdogan C, Yalcin R, Yazici Z, Hakyemez B, Parlak M, et al. Evaluation of Communication between Intracranial Arachnoid Cysts and Cisterns with Phase-Contrast Cine MR Imaging. AJNR Am J Neuroradiol 2005; 26: Vega SA, Obieta CE, Hernández RM. Intracranial arachnoid cyst. Cir Cir 2010;78: Pillai P, Menon S, Manjooran R, Kariyattil R, Pillai A, Panikar D. Temporal fossa arachnoid cyst presenting with bilateral subdural hematoma following trauma: two case reports. Journal of Medical Case Reports 2009, 3:53. Sprung C. Armbruster B, Koeppen D, Cabraja M. Arachnoid cysts of the middle cranial fossa accompanied by subdural effusions-experience with 60 consecutive cases. Acta Neurochir 2011; 153:75-84 Osborn A, Preece M. Intracranial Cyst: Radiologic Pathologic Correlation and Imaging Approach. Radiology 2006;239(3): Page 21 of 21