Ophthalmology
Question 54 of 97
A 54 year old man presents to the Emergency Department with diplopia. On examination you note ptosis of the right eye. The right eye is abducted and depressed at rest, with a fixed dilated pupil. A CT angiogram shows a cerebral aneurysm. Aneurysmal disease of which blood vessel is most likely to cause this patient's symptoms?
Answer:
The patient has signs of an oculomotor nerve palsy. Posterior communicating artery aneurysms are a cause of this palsy.Cranial Nerve Palsy
Neurology / Ophthalmology
Last Updated: 18th August 2022
Cranial nerve II: Optic nerve
| Cranial Nerve | Optic Nerve (CN II) |
|---|---|
| Key anatomy |
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| Function |
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| Assessment |
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| Clinical effects of injury |
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| Causes of injury |
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Cranial nerve III: Oculomotor nerve
| Cranial Nerve | Oculomotor Nerve (CN III) |
|---|---|
| Key anatomy |
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| Function |
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| Assessment |
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| Clinical effects of injury |
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| Causes of injury |
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Cranial nerve IV: Trochlear nerve
| Cranial Nerve | Trochlear Nerve (CN IV) |
|---|---|
| Key anatomy |
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| Function |
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| Assessment |
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| Clinical effects of injury |
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| Causes of injury |
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Cranial nerve VI: Abducens nerve
| Cranial Nerve | Abducens nerve (CN VI) |
|---|---|
| Key anatomy |
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| Function |
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| Assessment |
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| Clinical effects of injury |
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| Causes of injury |
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
