MIDDLE EAR AND TEMPORAL BONE TRAUMA

Transcription

1 MIDDLE EAR AND TEMPORAL BONE TRAUMA EVALUATION AND DIAGNOSIS History Chief Symptoms of Temporal Bone Fractures Symptom Differential Diagnosis Time of Onset Treatment Priority Hearing Loss Conductive or sensorineural and degree Early Not urgent Dizziness Peripheral or central Variable Not urgent Facial weakness Central or peripheral Important to determine Early intervention Facial hypesthesia Intratemporal cranial nerve V deficit or facial injuries Usually late onset if intracranial Spontaneous recovery is the general rule Diplopia Cranial nerve VI deficit or eye injury Usually late Spontaneous recovery is the general rule Hearing Loss -up to 40% HI pts suffer hearing loss -transverse fractures have greatest propensity for severe SNHL -longitudinal fractures more frequently with conductive and mixed hearing loss -labyrinthine or cochlear concussions high frequency SNHL with associated vertigo -mechanisms of SNHL: -disruption of otic capsule -concussion injury -NIHL -perilymphatic fistula -injury to auditory CNS Dizziness -often late complaints -notice once becoming ambulatory -causes of vertigo with trauma: -post concussion syndrome (most common) -concessive injury to membranous labyrinth -cupulolithiasis -disruptive injury to labyrinth -traumatic perilymphatic fistula -trauma-induced endolymphatic hydrops Facial Weakness -easily overlooked -determination of time of onset important -late-onset paresis or paralysis common after temporal bone trauma and may be delayed for days or weeks -areas of facial nerve injury: -longitudinal fractures: perigeniculate area -transverse fractures: labyrinthine segment -penetrating injuries: extra-temporal, stylomastoid portion, vertical segment of nerve F.Ling - Temporal Bone Trauma (1)

2 -mechanisms of injury: -bony spicules -perineural hematoma -transection -edema/swelling Otorrhea and Rhinorrhea -CSF leakage from temporal bone disruption Facial Hypesthesia and Diplopia -fractures involving Meckel s cave and the superior surface of the temporal bone or Dorello s canal beneath the petrosphenoidal ligament -prognosis usually very good Physical Examination -three commonly seen findings for temporal bone trauma -hemotympanum -postauricular ecchymosis (Battle sign) -periorbital ecchymosis (Raccoon eyes) -facial nerve weakness requires careful evaluation -CSF leakage: -diagnostic tests: chemical analysis, electrolyte determination, intrathecal dye injection, and -2 transferrin protein identification Radiologic Evaluation -high-resolution CT scanning with bone algorithms Temporal bone fracture type Longitudinal Transverse Location -through petrosquamous suture line and continues anterior to otic capsule -through superior EAC, middle ear, long axis of petrous pyramid -involve otic capsule or internal auditory canal Frequency 70-80% 20-30% Hearing loss -conductive -frequently hemotympanum and ossicular disruption -incudostapedial joint separation most common -sensorineural (usually severe) Facial nerve paralysis % -injury at the geniculate ganglion or in horizontal portion of nerve -50% Degree of trauma Complications -low to high -lateral blunt trauma -ossicular damage common -CHL -vertigo rare -bleeding in EAC -CSF leak occasionally (otorrhea) -usually high -occipital or frontal trauma -otic capsule and IAC rupture -SNHL -vertigo common -CSF leak common (rhinorrhea) F.Ling - Temporal Bone Trauma (2)

3 Other Tests -gunshot wounds or other penetrating trauma requires evaluation with angiography or MRA greater possibility of internal carotid artery injury -options for carotid injury: -embolization -surgical revascularization -ligation Hearing Tests -if early surgery is not a consideration, preliminary test is not critical; conductive losses may be repaired at any time and sensorineural losses have poor prognosis that are not influenced by treatment Facial Nerve Testing -if normal facial function exists in the early post-traumatic period, a delayed paralysis is always resolved with the return of function -patients who benefit from early surgery: -immediate paralysis, no clinical evidence of return of function, no electrical responses after 1 week -immediate paralysis and progressive decline of electrical responses to less than 10% of the normal side (evaluated with EnoG) -those with immediate paralysis and CT evidence of significant temporal bone disruption, indicating severe nerve laceration or sectioning, and injuries often accompanied by CSF otorrhea -neurotemesis evidenced by no return of function after 1 year Vestibular Testing: no role MANAGEMENT Symptom or Sign No Treatment Non-surgical Treatment Surgical Treatment Hearing loss May resolve if secondary to hemotympanum Amplification, conventional or CROS aid Tympanoplasty with or without middle ear reconstruction Dizziness Spontaneous resolution expected, unless bilateral or central vestibular lesion is incurred Pharmacologic vestibular suppression for acute stage Labyrinthine ablation or vestibular nerve section for long-term problems Facial Paralysis Complete recovery expected in cases of delayed onset Supportive eye care -physical therapy if long-term paralysis expected -structured rehabilitation with biofeedback techniques helpful to improve function and avoid synkinesis Decompression or repair of facial nerve Measures necessary for eye care (gold weight, or tarsorrhaphy) CSF otorrhea or rhinorrhea Spontaneous resolution in > 90% of cases Elevation of HOB; lumbar drainage Resorted to only after 2 weeks and failure of conservative measures -indications for surgery: -persistent leak -recurrent meningitis -persistent pneumocephalus F.Ling - Temporal Bone Trauma (3)

4 FACIAL NERVE EXPLORATION AND REPAIR -determine if fracture is otic sparing versus otic non-sparing -will determine type of approach -eg. longitudinal fracture with normal hearing: transmastoid approach -eg. transverse fracture with no hearing: translabyrinthine approach -eg. transverse fracture with normal hearing: middle fossa approach Transmastoid Approach -suitable only for lesions peripheral to geniculate ganglion -not appropriate for transverse fractures -lateral fracture defect involving mastoid cortex fracture line followed medially to facial nerve injury -bone chips removed from nerve: examined for stretching, compression, laceration, or transection -if intact decompression of epineural sheath in proximal and distal fashion until normal nerve encountered -partial transection repaired with onlay nerve graft -if > 50% axon separation interpositioning graft Transmastoid-Translabyrinthine Approach -used if hearing is not useful and site of facial nerve injury proximal to geniculate ganglion -usually for transverse fractures with involvement of otic capsule severe SNHL that will never recover -makes visible the entire intratemporal course of the nerve and brainstem origin -primary repair, grafting, or short-circuiting techniques are used from the posterior fossa to the parotid portion of the nerve Middle Cranial Fossa Approach -used to expose portion of facial nerve medial to geniculate ganglion if hearing remains intact Transmastoid Epitympanic Approach -fractures involving labyrinthine portion of the internal auditory canal with preservation of hearing REPAIR OF CEREBROSPINAL FLUID FISTULA -consideration of hearing necessary in planning approach -same procedures already described for nerve repair used for exposure of posterior or middle fossa -large bony defects reinforced with Silastic sheeting in addition to fascial grafting, or muscle plugs sutured to surrounding dura from the temporal side for small defects POSTOPERATIVE CARE -eye care essential for pts with facial paralysis -routine antibiotic coverage not instituted unless dura has been opened surgically -head elevation; steroids used in moderate doses if dura has been opened F.Ling - Temporal Bone Trauma (4)

5 COMPLICATIONS -failure of return of facial function -facial function should return within 6-12 months after repair, depending on the site of injury -if not returned EMG testing to identify early action potentials; CT scan to determine if any sites missed -meningitis -brain herniation -massive bleeding -cholesteatoma EMERGENCIES -obvious brain herniation into middle ear, mastoid or external auditory canal -massive bleeding from intratemporal carotid artery laceration F.Ling - Temporal Bone Trauma (5)