CN VI - abducens (ipsilateral movement of the eye in the temperal or lateral direction).CN V1 - 1st or ophthalmic division of the trigeminal nerve (ipsilateral sensation of the cornea, nare and forehead).CN IV - trochlear (contra lateral downward and medial eye movement).CN III - oculomotor (ipsilateral up and down eye movement, eyelid opening, pupillary constriction).impaired pupillary light response (CN II carries the light message to the CN III).CN I - olfactory (ipsilateral sense of smell).The approximate location of some of the major foramen are identified in Diagram 3 (note that in this diagram, the maxilla covers the frontal bone - the frontal bone is the true base of the anterior fossa). The base or bottom of the skull is continuous, with one large opening for the brainstem (called the foramen magnum) and several small foramens or canals that permit nerves and vessels to travel through the skull bones. How do the symptoms correlate to the area of injury? What are the signs of basal skull fracture?Īnterior Fossa Fracture - anosmia, epistaxis, rhinorrhea, subconjunctival hemorrhage, periorbital hemorrage (raccoon eyes, visual disturbances, altered eye movement, ptosis, loss of sensation to forehead, cornea and nare Middle Fossa Fracture - loss of sensation to lower face, ottorrhea, deafness, tinnitus, facial palsy, hemotympanium Posterior Fossa Fracture - echymosis behind the ear (battle sign), impaired gag reflex Catastrophic injuries can occur if there is a major disruption of the carotid artery (blood supply to middle and anterior cerebral cortex) or vertebral artery (blood supply to brainstem and posterior cerebral cortex), or if the brain stem is disrupted. Clinical findings consistent with basal skull fracture are generally the result of bleeding or CSF leaks into one or more of these foramen or into the sinuses, or due to damage of the nerve that traverses the bony canals. The base of the skull contains a number of bony channels or foramen that permit the passage of blood vessels and nerves through the bottom of the skull. CT may reveal suspicious fluid collections near a fracture if bleeding has occurred, or if damage to the dura resulted in a leak of CSF. Basal skull fractures are most frequently diagnosed by clinical findings, making clinical assessment skills critical.
In group 4, grafts may prevent adequate visualization of the IAC.Basal skull fractures are often not detectable with skull x-rays or even CT scan. In group 3 residual or recurrent tumor cannot be excluded. Whether follow-up in these groups is indicated needs to be determined. In groups 1 and 2, the MRI features correlate well with complete tumor removal. In group 4, follow-up in 1 of the 2 patients was stable. In group 3 follow-up showed 1 tumor recurrence (surgically confirmed) and 4 stable abnormalities. In group 2, dural enhancement remained unchanged in 5 patients and decreased in 3. Prospective 1- to 2-year follow-up studies were available in 8, 5, and 1 patients in groups 2, 3, and 4 respectively. We found four patterns (1) internal auditory canals (IAC) with nonenhancing soft-tissue strands, possibly scars or distorted residual nerves (8) (2) IAC with marginal enhancement-reactive dura mater (16) (3) IAC with contrast-enhancing globular tissues suggesting residual or recurrent tumour (5) (4) high-signal intensity in the IAC before contrast medium administration, probably related to graft with fat/fascia/muscle (2). Follow-up MRI was performed after 1-2 years on patients with questionable abnormalities. Prospective baseline MRI was obtained on 31 patients who had ``total`` removal of acoustic schwannoma 6 months to 9 years previously.
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