My 14 yr old son recently underwent a CT scan of his sinuses due to a diagnosis of chronic sinusitis. Haller Cells were evident bilaterally, with bilateral maxillary and ethmoid sinus inflammation (mild to moderate) with suggested small underlying polyps and a septum deviated to the left.

My main questions are:
1. Is this considered a small cyst?
2. What are the chances of it growing and enlarging?
3. What, in your opinion, is the route most likely to be taken to cure/ease symptoms of above conditions?

Posted by: Maria/ MDHealth Forum.com Team

The brain and the spinal cord are enclosed within three meninges or membranes. The outermost layer is the dura matter, next layer is the arachnoid membrane and the innermost layer is the pia matter. The brain floats in a clear fluid called cerebrospinal fluid (CSF). The meninges and the CSF protect the central nervous system. The cerebrospinal fluid flows through a cavity which lies under the arachnoid membrane, this cavity is known as the subarachnoid space.

Arachnoid cysts are benign sacs in the arachnoid membrane. These sacs are filled with a CSF-like fluid. They are usually incidentally found in in CT scan or MRI that are done for other clinical reasons. Primary arachnoid cysts are present at birth and were thought to be formed as a result of developmental irregularities in the brain or spinal cord that arise during the first few weeks of gestation. Secondary arachnoid cysts, on the other hand, develop as a result of head injury, tumors, meningitis, or as a complication of brain surgery. The size and location of the cyst determine the severity and onset of symptoms. For example, a small cyst may not cause any symptoms at all, and may be discovered accidentally during an unrelated examination. Large cysts, however, can cause the head to change its shape or to increase its size. Symptoms experienced by individuals with a larger cyst include headaches, seizures, accumulation of a pronounced amount of cerebrospinal fluid, increased pressure inside the cranial cavity, delay in mental and physical development, and altered behavior.

The treatment depends largely on the location and size of the cyst. If the cyst is small, not disturbing surrounding tissue, and not causing symptoms, some doctors may not consider treatment. But how small is small? I didn’t find specific information from the net about the exact dimensions of arachnoid cysts for them to be considered as small in size. This article from the official journal of the American Journal of Pediatrics shows an MRI report of an 11 -month old patient, the size of the cyst was 3.2 x 4.8 cm. The fluid collection that was described in the CT scan result that you have posted is quite small if you will compare that with the size of the cyst mentioned in the case report. But of course you need the opinion of your doctor to confirm whether the suspected arachnoid cyst detected on your son’s CT scan can be considered small. I asked a neurosurgeon about what he thinks of the fluid accumulation detected in your son’s brain, and he said that considering its size, it is not likely the one that has been causing your son’s symptoms. You too should discuss this with your son’s doctor, your doctor’s evaluation would determine if further tests should be done. MRI is considered as a definitive diagnostic procedure, other than detecting the exact location of the cyst, it also demonstrates the extent, and relationship of the cyst to the nearby brain areas.

I’ve read that arachnoid cysts usually remain stable in size, there are also reports of cysts slowly enlarging. For small arachnoid cysts that cause minimal symptoms, most doctors would opt for conservative treatment with regular clinical and radiological follow up like CT scan or MRI yearly to find out if the cyst is growing.

To know what should be done to relieve the symptoms, I think it is important first to determine what has been causing them. Fatigue alone, is a symptom numerous etiologies. One of the goals for treating nasal polyps is to decrease their size, it can be done by administering drugs or surgery. Since allergy is known to predispose chronic inflammation of the sinuses and nasal passages, nasal sprays containing corticosteroids, oral steroids or antihistamines may be prescribed by the doctor. To manage chronic infection, antibiotics are also given. Only your doctor can tell you which is the best treatment for your son based on symptoms presented and results of tests.

This blog entry is for general information only. Please discuss your son’s symptoms with his doctor.

References:

http://www.ninds.nih.gov/disorders/arachnoid_cysts/arachnoid_cysts.htm
http://emedicine.medscape.com/article/336489-overview
Cameron AD. “Psychotic phenomena with migraine and an arachnoid cyst”, Progress in Neurology and Psychiatry 2002 Mar-Apr 6
http://www.ijccm.org/article.asp?issn=0972-5229;year=2008;volume=12;issue=1;spage=42;epage=45;aulast=Pillai
Artico M, Cervoni L, Salvati M, Fiorenza F, Caruso R. Supratentorial arachnoid cysts: Clinical and therapeutic remarks on 46 cases Acta Neurochir (Wien) 1995;132:75-8
http://pediatrics.aappublications.org/cgi/content/full/110/1/e13

Tags: arachnoid cyst, chronic sinusitis, Fatigue, Headache, nasal polyps