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BRAIN HERNIATION IN AN OPERATED MASTOID CAVITY

HARITOSH K VELANKAR*, KS PRADHAN**
*Associate Professor in ENT; **HOD Ent, Rajawadi Hospital, Ghatkoper, Pad DY Patil Medical College.

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Many cases have been reported to herniation of Dura (meningocoele) and/or Brain, (meningoencephlocoele), into the mastoid and the middle ear. The aetiological factors are felt to be, chronic otomastoiditis, congenital dehiscence, fracture of skull base, spontaneous and most common, post mastoidectomy surgery. The commonly herniated part is the temporal lobe, but cerebellar herniation are also reported. Surgical approaches in the treatment of brain herniation into the mastoid or middle ear are, neuro surgical, otosurgical and combined.

INTRODUCTION

There are more than one hundred fifty cases of brain herniation into the middle ear and mastoid been reported in world literature. The various reasons attributed to such pathology were namely, long standing mastoiditis, previous temporal lobe fracture, spontaneous herniation and most important common cause was post operative to mastoidectomy. One such case is reported.

CASE REPORTS

A seven year old child came to our OPD with a complaint of left ear discharge for more than three years. Clinical finding, revealed an Attic Cholesteatoma. Diagnosis was confirmed after investigations, like mastoid X-rays and ear microscopy. Subsequently the patient was then operated and, a modified radical mastoidectomy was done. The malleus and incus were absent, after clearance of cholesteatoma, temporalis fascia graft was kept and type 3 tympanoplasty done. The dural plate and sinus plate were normal. Patient was discharged after week from the hospital. The patient did not come for follow up later as he went to his house in rural area of Maharashtra. Approximately, after one year the patient came to the OPD, with purulent ear discharge from the same ear. There was no h/o fever, vomiting, headache or watery discharge.

On examination, there was a smooth swelling arising from the roof of the operated mastoid cavity, and involving almost the whole mastoid cavity, associated with granulations and purulent discharge. Patient was afebrile, pulse and blood pressure were normal.

Investigations like, X-ray mastoid showed operated cavity with sclerosis on the left side. Secretions from the ear were tested, but did not reveal any evidence of CSF. CT scan showed, a bony defect in the tegmen tympani and anterior cortex of petrous bone on left side with associated prolapse of Dura and part of the temporal lobe of brain.

Fig. 1: CT scan coronal section showing brain herniation through tegmen tympani.	Fig. 2: CT scan axial section showing brain herniation.

Operative Notes

Since it was a small defect we decided to repair the herniation by transmastoid approach.

-postaural incision made.

-conchal cartilage removed of the same ear, for repair of the defect.

-mastoid cavity exposed, posterior bony overhang drilled out.

-defect seen in the dural plate was approximately 1 cm by 1 cm.

-dura adherent to the meatal skin, was separated, without damaging the dura.

-the heriation was reduced, and the opening closed with the piece of concal cartilage, and covered with temporalis fascia.

-cavity was packed with gel foam.

The patient was asked to report follow-up, strictly for next three months every weekly. There was no recurrence seen and the cartilage kept was nicely in place.

DISCUSSION

There are many cases reported of herniation of dura (meningocoele) and/or brain (meningoencephalocoele), into the mastoid and the middle ear. The aetiological factors are felt to be, chronic otomastoiditis, congenital dehiscence, fracture of skull base, spontaneous and most common, post surgical (mastoidectomy). Herniations were classified as pedenculated or sessile. They were associated with infection, CSF leak, and neurological complications. They are also associated with otological problems such as hearing loss, and trapped squamous epithelium. The most common cause was identified as small iatrogenic injury during mastoidectomy. The cases and literature reported, support that, dural injury is necessary for herniation, and if the arachnoid remains intact, a meningoencephalocoele results. The potential of CSF leak into the ear and recurrent meningitis is common. If the arachnoid is not intact, an encephalocoele results which predominently presents as a mass without a CSF leak. The commonly herniated part was the temporal lobe, but cerebellar herniation are also reported. Surgical approaches in the treatment of brain herniation into the mastoid or middle ear are, neurological, otological and combined.

Otological - mainly transmastoid, done in very small defects. Cartilage, bone chips or temporalis fascia is used to repair the defect.

Neurological - by middle cranial fossa approach or temporoparietal craniotomy. Combined-advocated in very large herniation.

REFERENCES

1.Iurato S, Ettorre GC, Selvini C. Brain herniation into middle ear. Laryngoscope 1989; 99 (9) : 950-4.

2.Soubere C, Langman AW. Combined mastoid/middle cranial fossa approach. Skull base Surgery 1998; 8 : 185-9.

3.Fenstra L, Sanna M, Zini C. Surgical treatment of brain herniation. American J Otol 1985; 6 (4) : 311-5.

4.Bartels L, Luk LJ, Balis G. Endaural brain hernia. Ame J Otol 1885; Suppl 121-5.

5.Glassock ME 3d, Dickens JR, Diagnosis and surgical management of brain herniation. Laryngoscope 1979; 89 (11) : 1743-54.

6.Ramanikanth TV, Smith MC, Ramalingam KK. Post auricular cerebellar encephalocoele. J Laryngol Otol 1990; 104 (12) : 982-5.

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