Multidisciplinary Team Performs Innovative Repair of Temporal Bone Defects
Neurotologists, neurosurgeons, neuroradiologists, and neuro-ophthalmologists at Brigham and Women’s Hospital (BWH) are providing advanced multidisciplinary evaluation and treatment for patients with temporal bone defects.
“We are seeing many patients referred for cerebral spinal fluid leaks and subsequent identification of encephaloceles with a skull base temporal bone defect,” said C. Eduardo Corrales, MD, a neurotologist in the Division of Otolaryngology at BWH. “Traditionally, primary causes have included traumatic temporal bone fractures, but more patients today are presenting with idiopathic conditions.”
Etiology of Temporal Bone Defects and CSF Leaks
Dr. Corrales recently published a paper detailing levels of dehiscence in the temporal bone, superior canal, and posterior canal demonstrated by computed tomography scans (CT) in children less than seven years of age (Otol Neurotol. 2015 Sep;36(8):1383-9.). While dehiscence of the canals was commonly seen in the CT scans of infants in the first six months of life, the prevalence decreased with increasing age as the bone overlying the canals increases in thickness.
“We know that the temporal bone thickens by the time children reach seven years-of-age, but we believe that it may be thinner in some individuals than others and may wear faster in these patients as they age,” said Dr. Corrales. “We have also seen an increase in the incidence of cerebral spinal fluid leaks in patients who are obese or morbidly obese with obstructive sleep apnea, so it’s highly likely that there are multiple factors contributing to the rise of these cases.”
Comprehensive Surgical Repair
Specialists at BWH are among few in the country to offer highly advanced surgical repair of skull base temporal bone defects. Dr. Corrales collaborates with BWH neurosurgeon Ian F. Dunn, MD, in the Skull Base Program at BWH to perform surgical repair of temporal bone defects, generally using a middle cranial fossa approach. Together, they have surgically treated more than 30 patients with very good outcomes. After craniotomy, view of the middle cranial fossa floor shows the extent of the defect and provides access to encephalocele, temporal bone defects, and superior canal dehiscence for treatment. Repair is performed using autologous temporalis fascia, calvarial free bone graft, and bone paste, as well as bone wax and hydroxyapatite (See Case Study.) Titanium mesh is used to place the craniotomy bone.
Case Study: Multidisciplinary approach for repair of skull base defects
A 33-year-old woman presented with right muffled hearing, ear pain and imbalance. She was seen by her PCP who diagnosed her with acute otitis media and prescribed a course of antibiotics. There was an initial improvement, but symptoms recurred shortly after. She was referred to a local Otolaryngologist who diagnosed her with right middle ear effusion and prescribed a second course of antibiotics and prednisone. Because of her persistent symptoms, a CT scan of the temporal bones was ordered. She had a diagnosis of pseudotumor cerebri (benign intracranial hypertension) in her teens and had been treated with furosemide, acetazolamide and prednisone.
The audiogram showed a maximal conductive hearing loss on the right. CT scan showed a tegmen dehiscence with a large associated encephalocele. A contrasted MRI showed a large encephalocele filling the full extent of the mastoid and middle ear. The Patient decided to proceed with surgery.
Figure A: schematic drawing showing a tegmen dehiscence with associated encephalocele
Figure B: a coronal contrasted MRI demonstrating an encephalocele protruding into the mastoid and middle ear
Figure C: the coronal CT scan with a large dehiscence of the tegmen (arrows indicated dehiscence in all figures)
Figures D and E: comparison between preoperative and postoperative CT scans.
A middle cranial fossa craniotomy approach was performed with full thickness calvarial bone graft used to reconstruct the tegmen dehiscence.
Patient had an uneventful recovery with resolution of her symptoms and recovery of her hearing. She has a contralateral thin tegmen that we are currently observing. She is being managed in a multidisciplinary fashion, and Neurology is following her for benign intracranial hypertension.
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