Surgical management of CSF otorrhoea (a case report).
Four cases of CSF otorrhoea following surgery are presented. The etiopathology and its surgical management are discussed.
In the well-pneumatised temporal bone, the temporal lobe of the brain is separated from the middle ear and the mastoid process by a thin layer of bone known as the tegmen. Congenital defects, infection and trauma can alter this structure in such a way that CSF otorrhoca results.
CSF egress from the subarachnoid space into the pneumatised spaces of the temporal bone is most commonly the result of fracture associated with laceration of dura and arachnoid. Intra-cranial surgery that extends through or into the temporal bone is the next most common cause. Exit of CSF from the pneumatised spaces to the external environment is frequently through laceration of the tympanic membrane or through the surgical wound. When these external avenues are intact, the fluid may exit through the custachian tube presenting as a CSF rhinorrhoea.
The complications of CSF otorrhoea are potentially lethal, thereby emphasising the necessity for early recognition and correct management of these patients.
Four cases of CSF otorrhoea sucessfully operated on in our department are reviewed in detail. Two of these were following intracranial surgery for acoustic neuroma removal and two were following surgical treatment for chronic otitis media.
SM, an 18-year-old female presented with the chief complaint of otorrhoca from the right car following a mastoidectomy. On examination, the patient had an open cavity with granulations over the dura in the region of the tegnien. CSF was seen to be flowing out from this area of granulation. The X-ray mastoid showed a break in continuity of the teginen.
The patient's mastoid was explored via a post-aural approach and the site of leak found in the above mentioned area. Granulation tissue was removed. The dura was elevated around the tear from the middle cranial fossa. The site of leak was patched with temporalis fascia which was tucked in between the tel-nien and elevated dura. This was supported by free muscle graft and gel foam. A pack was kept in the cavity, which was removed after seven days. The leak stopped completely following surgery. The patient has been asymptomatic for the past nine months.
MP, a 65-year-old female presented with intermittent rhinorrhoea from her right nostril. She had undergone surgery for the removal of an acoustic neuroma by the sub-occipital approach. On examination, she had a dull, tympanic membrane, which showed pulsatile movement. She was subjected to a nasal endoscopic examination, which revealed a CSF leak from the eustachian tube opening. An exploratory tympanotomy was performed. The entire middle ear was bathed by CSF, which was coming from the attic region. The mastoid was explored whereupon a defect was found in the sinodural angle. This was repaired in the same manner as described for case 1. She too recovered uneventfully and has been asymptomatic for the past seven months.
PM, a 35-year-old female presented with CSF rhinorrhoea from her right nostril. She too had undergone acoustic neuroma removal by the sub-occipital approach done prior to presentation.
On exploration, a defect was found in the posterior fossa dura towards the mastoid tip. This was plugged with a piece of temporalis muscle and covered with fascia. Post-operatively, the patient was asymptomatic for 11 days. On the 12th day, she again complained of rhinorrhoca from the right side. On re-exploration a second site of CSF leak was found. This leak was front the perilabyrinthine cells. The leak was followed medially and found to be occurring from the posterior surface of the internal auditory meatus. This was plugged with muscle and covered with fascia and gel foam. The patient has had no leak for the past six and a half months.
SK, a 38-year-old male complained of CSF rhinorrhoea from the left nostril, and a watery discharge front the left external ear canal and post-aural wound. He had undergone a simple mastoidectomy for acute mastoiditis. He developed a leak on the fifth post-operative day. On examination he had a small anterior perforation through which CSF was leaking. On exploration, CSF leak was found from the cells between the posterior semicircular canal and the sigmoid sinus. This was plugged with temporalis muscle. A temporalis fascia graft was used to cover this site. A temporalis muscle sling was used to support the fascia. The leak stopped immediately and for the past five months the patient had no complaints.
CSF otorrhoea arising from defects in the tegmen and middle fossa may be spontaneous or secondary to trauma, chronic ear disease, tumour or surgical treatment. Accidental trauma is thought to be the commonest cause of CSF otorrhoea, but all the cases encountered in our series were following surgery. The two cases, which were following mastoidectomy presented with CSF otorrhoca whereas the two cases which were following removal of acoustic neuroma presented with CSF rhinorrhoea.
The popularity of the sub-occipital approach for acoustic neuroma removal is partly because of the lower incidence of CSF leaks compared with the translabyrinthine route, however Robson et al show a 17% incidence of CSF leaks requiring operative intervention. Drilling of the petrous bone will often open up mastoid air cells, which communicate with the middle car cavity. Gordon et al reported two cases of CSF leak through the petrous bone following a sub-occipital approach, drawing attention to this air cell tract, and emphasising the importance of closing this potential site for a leak, at the time of the original operation.
While doing a mastoidectomy, a thorough knowledge of the surgical anatomy of the temporal bone is very essential. The surgeon must be careful while drilling near the tegmen and posterior fossa dura. A large diamond drill should always be used to prevent trauma. Even if a CSF leak is observed during the course of surgery it should be immediately scaled with fascia and muscle.
CSF otorrhoca arising from defects in the tegmen and middle fossa dura can be managed by an intra-cranial repair, extracranial transmastold or a combined approach. The intra-cranial and combined approaches offer advantages in direct visualization and precise intra- and/or extra-dural intra-acranial placement of a graft secured by sutures. The potential disadvantage is the morbidity associated with a temporal craniotomy.
All our patients were operated by the extra-cranial transmastoid approach. This approach is preferred because of the otologist's familiarity with temporal bone anatomy. By this approach the entire middle fossa dura from the tegmen tympani to the sinodural angle and the posterior fossa dura from the sinodural angle to the mastoid tip can be exposed if necessary. After delineating the entire damaged area, the defect is plugged with either muscle or fascia. The entire cavity is then packed with muscle or gel foam.
This technique was successful in both the patients with a postmastoidectomy leak. Amongst the cases of leaks following acoustic neuroma excision one patient required re-exploration, which successfully stopped the leak.
We are grateful to our Dean, Dr. (Mrs.) P. M. Pai, Seth GS Medical College and King Edward Memorial Hospital, Mumbai, for allowing us to publish this article.