PEMPix is the American Academy of Pediatrics Section on Emergency Medicine’s annual visual diagnosis competition. This year, in addition to the 10 finalists Maneesha Agarwal will be presenting at the National Conference and Exhibition we will be sharing four cases online in advance of the conference. This is the first of the four cases.

This case was submitted by
Dr. Andrea De Jesús Martínez
Chief PEM Fellow at Baylor College of Medicine | Texas Children’s Hospital

Instagram: @bcm_pemfellows

Co-author: Benjamin Silva, MD, MPH

The Case

A 4-year-old male with no significant past medical history presents with headache and vomiting. About 2 weeks prior, he had an ED evaluation after a 2-3 foot fall onto a carpeted floor with subsequent vomiting. At that visit, his physical exam was normal. He had a CT scan (depicted below) that was reviewed by the neurosurgery team, and he was cleared for discharge home.

During this ED visit, the family notes that the child has had 1 week of vomiting whenever he eats. They also note that he has been waking up in the early morning with a headache that is self-resolving and occasional associated vomiting. The patient has had improving activity and energy since his fall and initial ED evaluation 2 weeks prior.

During this second ED visit, his physical exam including vital signs and mental status remains normal. His neurologic exam reveals an alert child with GCS of 15. No facial asymmetry. Moves all extremities equally against gravity. Intact sensation to light touch bilaterally. No CN II-XII deficits noted. A second CT scan is obtained with relevant cuts depicted below.

What’s the Diagnosis?

A. Epidermoid cyst
B. Non-accidental trauma
C. Ruptured arachnoid cyst
D. Mega cisterna magna
E. Post-traumatic leptomeningeal cyst

C. Ruptured Arachnoid Cyst

Arachnoid cysts are benign extra-axial cystic lesions that are filled with cerebrospinal fluid (CSF). They are usually incidental findings that are completely asymptomatic. However, these cysts can rupture (occurrence rate ~2-6%) and cause subdural hygromas, an accumulation of CSF in the subdural space due to separation of the arachnoid layer from the dura. Cysts larger than 5cm in size increases the risk of rupture, which can be precipitated by even minor head trauma.

Rarely, an arachnoid cyst rupture with subsequent subdural hygroma will result in increased intracranial pressure (occurrence rate <1%). Symptoms typically evolve in the following days to weeks after rupture. Increased intracranial pressure is an indication for surgical intervention.

This patient had a subsequent brain MRI that also revealed papilledema. He also developed hypertension with bradycardia prompting surgical intervention. He initially underwent a right craniotomy with cyst fenestration. He then developed a large pseudocyst requiring placement of a permanent ventriculoperitoneal shunt.

References

Almousa, Abdulelah S et al. “Spontaneous Rupture of Arachnoid Cyst in a Child: A Rare Case Report.” Cureus vol. 15,1 e33652. 11 Jan. 2023, doi:10.7759/cureus.33652

de Araújo Neto, Francisco Barbosa et al. “Post-traumatic intraosseous leptomeningeal cyst.” Radiologia brasileira vol. 51,2 (2018): 126-128. doi:10.1590/0100-3984.2016.0166

Furtado, Leopoldo Mandic Ferreira et al. “Intracranial arachnoid cyst rupture after mild TBI in children: have we underestimated this risk?.” BMJ case reports vol. 12,4 e228790. 30 Apr. 2019, doi:10.1136/bcr-2018-228790

Jafrani, Ryan et al. “Intracranial arachnoid cysts: Pediatric neurosurgery update.” Surgical neurology international vol. 10 15. 6 Feb. 2019, doi:10.4103/sni.sni_320_18

Khilji, Muhammad Faisal et al. “Spontaneous Arachnoid Cyst Rupture with Subdural Hygroma in a Child.” Case reports in emergency medicine vol. 2016 (2016): 6964713. doi:10.1155/2016/6964713

Kim, Ga-Eun et al. “Radiologic Follow-up of Ruptured Arachnoid Cysts With or Without Hemorrhage: Five Case Reports and a Review of the Literature.” Brain tumor research and treatment vol. 11,3 (2023): 210-215. doi:10.14791/btrt.2023.0013

Rajesh, A et al. “Traumatic rupture of arachnoid cyst with subdural hygroma.” Journal of pediatric neurosciences vol. 7,1 (2012): 33-5. doi:10.4103/1817-1745.97620

Shrestha, Rajendra, and Chao You. “Spontaneous chronic subdural hematoma associated with arachnoid cyst in children and young adults.” Asian journal of neurosurgery vol. 9,3 (2014): 168-72. doi:10.4103/1793-5482.142739

White, Matthew L. and Joe M. Das. “Arachnoid Cysts.” StatPearls, StatPearls Publishing, 2 February 2024.

Wittschieber, D et al. “Understanding Subdural Collections in Pediatric Abusive Head Trauma.” AJNR. American journal of neuroradiology vol. 40,3 (2019): 388-395. doi:10.3174/ajnr.A5855