Re: arachnoid cyst

Posted By CCF NSG MD /gsh on November 10, 1998 at 19:34:39:

In Reply to: arachnoid cyst posted by John on November 07, 1998 at 22:04:43:






47 year old male presents with congenital "plum sized" arachnoid cyst in left temporal lobe.  Cyst has also surrounded brain stem.  
Initial complaint was a faint or seizure-like event while driving. Patient reported total loss of vision and disorientation and loss of coordination causing him to slump over for 2-3 seconds.  Based on account of passenger in vehicle, patient heard everything during the event, thus, seizure activity not deemed likely by neurologist.   Rather, neurologist feels a cardiovascular causation more likely.
Patient seeking more information regarding arachnoid cyst...
1. Can the cyst contain malignant cells as with other types of cysts?
2. What besides vision, hearing, seizure, or behvioral effects can such a cyst induce? What exactly are the symptoms that can be expected, if any?
3. Can it affect any gross motor skills?
4. How soon after the baseline MRI would a second MRI indicate the speed of growth (if any) of the cyst?
5. Given the size of the cyst, would not aggressive attempt to aspirate the cyst be a prudent treatment to prevent symptoms?
Thank you for your response and any other suggestions you might have regarding additional resources as there appears very little literature on this type of brain anomaly.
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Dear John,
An arachnoid cyst is a congenital condition where the coverings of the brain form an abnormal collection of spinal fluid.  They are completely benign.  Arachnoid cysts can range from small and asymptomatic to large and compressing significant amounts of brain.  They cause deficits by mass effect and pushing on different areas of the brain.  When they become symptomatic with headaches, numbness or weakness, surgery may be considered.
Arachnoid cysts may be drained in a number of ways.  A needle may be used to drain the cyst, but is will reform quickly.  Surgery can be done to open the cyst to drain internally or, alternatively, a shunt may be left in the cyst and tunnelled into the abdomen to drain.  
Speak to your surgeon about whether the noted problems are related to the arachnoid cyst.  This will be a good indicator as to whether surgery will be beneficial or not.
Incidentally, there is no known association with benign positional vertigo.
Good luck.