Author Topic: Saccus decompression operation  (Read 9363 times)

Offline Alec

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Saccus decompression operation
« on: Feb 06 2007, 02:37 PM »
Here is a good description of the Saccus operation.

An ear operation used for those with Meniere's syndrome. It aims to stop the attacks of vertigo whilst preserving remaining hearing in that ear.

Anatomy and Physiology

The bone of each ear contains a series of tiny channels called the labyrinth. These contain thin membranous tubes that make up the inner ear. This has two principal parts; the cochlea, for hearing and the vestibular apparatus, for balance and motion sense.

The vestibular apparatus is composed of several parts: the Semicircular canals detect acceleration or deceleration movements in all directions; the Utricle and Saccule detect the angle of the head and the Saccus Endolymphaticus, this appears to function as a reservoir that absorbs or secretes the fluids of the inner ear.

The Saccus is like a small flat bag. It lies on the surface of the bone behind the inner ear, inside the skull but outside the thick dura membrane covering the brain.

In Meniere's syndrome there is swelling and increased fluid pressure (called Endolymphatic Hydrops) within the membranes of the vestibular apparatus. The aim of the operation is to relieve this pressure. There have been a number of criticisms of this theory and a famous study in Denmark appears to show that this cannot possibly be how the operation works. Others have strongly supported the operation because of the many reports of its efficacy, whatever the actual reason.


Anaesthetic

The operation is usually performed under general anaesthesia.

Surgical Technique

An incision is made over the mastoid process, which is the bony lump behind the ear. Under an operating microscope a hole is slowly drilled and enlarged to find the vestibular apparatus and Saccus. Usually it is opened and a small piece of plastic inserted. This is intended to facilitate drainage and remains in the mastoid. Sometimes the sac is simply exposed, to allow it to decompress, or part of the sac wall is removed in order to 'ablate' it. (Some surgeons believe that it is damaging the sac in some way that is the crucial factor). The operation does not affect the ear canal or eardrum.

Length of Operation

The operation takes about 1 to 2 hours.

Time in Hospital and Post-Operative Management

One night in hospital is usual. There may be a bandage to protect the ear for a few days. Any stitches are removed after about a week or they may be absorbable. Regular mild painkillers may be needed for a week. Some people may experience vertigo requiring medication.

Time Off Work and Post-Operative Limitations

About 2 weeks off work is usual. Wearing anything in or over the ear may be uncomfortable during this time. There is no restriction of bathing. Caution is required with swimming and driving until any imbalance has stabilised.


Risks and Complications


Hearing loss: 2% of patients experience profound loss of hearing in that ear.

Cerebro-spinal fluid leak: 5% risk of leakage of fluid from around the brain into the ear. In most cases this seals without treatment. Occasionally repair is needed.

Facial nerve weakness: 0.2% (2 in 1000) risk of weakness or paralysis of the nerve. This means that the facial muscles on that side become loose and sag. Eye or lip closure becomes difficult. Generally any weakness is temporary or partial but complete total paralysis of that side of the face is possible, though very rare.


Outcome/Prognosis

Vertigo: Complete resolution in 50 - 75% of patients. There is a small relapse rate over a 10-year period. 1 in 10 to 1 in 20 people may need the operation redone later.

Hearing: 30 - 40% of patients have improved hearing. More than 50% of patients either maintain or increase their hearing in that ear. More than 90% maintain or increase hearing or at least slow down the previous rate of hearing loss.

Tinnitus: 50% experience reduced or absent tinnitus noise in that ear.

Pressure: The sensation of pressure or fullness in or around the ear is reduced in 50% of patients.

Other Treatments

Counselling: about Meniere's and its usual course. It's relationship to stress.

Dietary: possible aggravating factors that have been considered are salt, excessive fluid intake, caffeine, tobacco, chocolate and alcohol.

Drugs: prochlorperazine, cinnarizine, steroids, diuretics ,betahistine and others. Some are used as prophylactics and others for acute episodes of vertigo.

Surgical treatments: some are aimed to preserve hearing, others will remove hearing from that ear;


Grommet: simple insertion of this ventilation tube in the drum sometimes helps. How it does so is unclear. Replacement may be needed roughly every twelve months.


Intratympanic gentamicin injections: these may be direct or through a grommet or catheter placed in the eardrum. They may be effective by damaging the vestibular apparatus enough to stop it causing vertigo. In about 10% of patients they cause some hearing loss. Usually 2 or more treatments are given and later repetition may be required.

Labyrinthectomy: very effective at stopping vertigo but will always remove all remaining hearing in that ear. Up to 1 in 3 patients develop Meniere's in both ears so an operation that does not damage hearing is preferred in most cases unless there is almost no hearing left in that ear or other measures fail.

Vestibular neurectomy: this cuts the nerve to the balance organ. It is very effective for vertigo. It aims to save hearing but there is a 5% risk of loss. Risk of facial nerve damage has been variously reported as between 3 and 44%. It is an operation close to the brain and risks are more significant.

Alternative / Complementary Treatments

Ginger: some claim this is effective for motion sickness.

Acupuncture: some evidence of benefit for nausea. Gentle pressure on points on the wrist by a wristband is claimed to help motion sickness.

Links

http://oto.wustl.edu/men/


http://www.skullsurgery.aust.com/html/menieres_disease.html

http://www.entnet.org/meniere.html

http://www.tchain.com/otoneurology/disorders/menieres/menieres.html


Mr J Cook FRCS

Alec (forum Moderator)

Whenever I hear the term, 'let's go for a spin', it makes me cringe.