#july2020amc1
A 10-year-old boy presents to the Emergency Department. Last week he had an upper respiratory tract infection, following which he quickly developed swelling around his right eye and was unable to open it. Now he has bilateral periorbital swelling, a temperature of 40oC and a Glasgow Coma Scale score of 13. He has a contrast enhanced CT scan which demonstrates a cavernous sinus thrombosis. Which one of the following symptoms/signs would not be present?
A. Absent corneal reflex
B. Anaesthesia over the angle of the mandible
C. Ophthalmoplegia
D. Lateral rectus palsy
E. Absent swinging light pupillary reflex
Explanatory Notes:
Anaesthesia over the angle of the mandible. Infected thrombus within the cavernous sinus may cause a variety of cranial nerve palsies affecting those nerves that are directly
related to the sinus.
Cranial nerves III, IV, V1 and V2 run within the lateral wall of the cavernous sinus.
Lesions of CN III in isolation causes the globe to rest in downward, lateral gaze, and interruption of the efferent limb of the pupillary
reflexes to light (tested by the swinging light reflex) and accommodation. Lesions of CN IV causes diplopia in downward gaze doe to paralysis of Superior Oblique muscle; while lesions of CN VI cause paralysis of lateral gaze (Lateral Rectus muscle). A combined lesion of CN III, IV and VI causes complete ophthalmoplegia.
CN V1, the ophthalmic nerve supplies sensation to the upper face, skull and eye, so a lesion of it affects the afferent limb of the corneal reflex.
Sensation to the angle of the mandible is supplied by the mandibular nerve (CN V3), which is not directly related to the cavernous sinus.
A 10-year-old boy presents to the Emergency Department. Last week he had an upper respiratory tract infection, following which he quickly developed swelling around his right eye and was unable to open it. Now he has bilateral periorbital swelling, a temperature of 40oC and a Glasgow Coma Scale score of 13. He has a contrast enhanced CT scan which demonstrates a cavernous sinus thrombosis. Which one of the following symptoms/signs would not be present?
A. Absent corneal reflex
B. Anaesthesia over the angle of the mandible
C. Ophthalmoplegia
D. Lateral rectus palsy
E. Absent swinging light pupillary reflex
Explanatory Notes:
Anaesthesia over the angle of the mandible. Infected thrombus within the cavernous sinus may cause a variety of cranial nerve palsies affecting those nerves that are directly
related to the sinus.
Cranial nerves III, IV, V1 and V2 run within the lateral wall of the cavernous sinus.
Lesions of CN III in isolation causes the globe to rest in downward, lateral gaze, and interruption of the efferent limb of the pupillary
reflexes to light (tested by the swinging light reflex) and accommodation. Lesions of CN IV causes diplopia in downward gaze doe to paralysis of Superior Oblique muscle; while lesions of CN VI cause paralysis of lateral gaze (Lateral Rectus muscle). A combined lesion of CN III, IV and VI causes complete ophthalmoplegia.
CN V1, the ophthalmic nerve supplies sensation to the upper face, skull and eye, so a lesion of it affects the afferent limb of the corneal reflex.
Sensation to the angle of the mandible is supplied by the mandibular nerve (CN V3), which is not directly related to the cavernous sinus.
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