A 15-year-old boy is brought to paediatric A&E by his parents. He complains of severe headache and vomits while waiting to be seen. He gives a history of polyuria and confusion with visual fi eld defects. On examination he appears to be significantly shorter than average height for his age. He does not have signs of meningitis. His past medical history and family history reveals no additional clues to his presentation. He denies using drugs.
Which of the following investigations may help in clinching the diagnosis?
C. The presentation here is consistent with craniopharyngioma. It is a benign, slow growing tumour involving the pituitary gland. The clinical presentation is usually insidious with the most common presenting symptoms being headache, endocrine dysfunction, and visual fi eld disturbances. The headache may be positional and slowly progressive. Hypothyroidism, adrenal failure, and diabetes insipidus are the common endocrine disturbances noted. Young patients may have growth failure and/or delayed puberty. Visual fi eld defects are due to pressure effects on the optic nerve route. Bitemporal hemianopia is the most common problem due to pressure at the chiasma. The anatomic location of the craniopharyngioma may be classified into prechiasmal (associated with optic atrophy), retrochiasmal (associated with signs of increased intracranial pressure such as papilledema), or intrasellar (associated with headache and endocrine dysfunction). The diagnosis is strongly suggested by imaging studies. The appearance of a suprasellar or intrasellar calcified cyst is considered to be the radiological hallmark. CT scan is the most sensitive method as calcifications are easily picked up as high-density areas. MRI is very helpful for neurosurgeons to plan a surgical approach.
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Which of the following structures may be causally related to the presentation?
E. The embryogenetic theory of craniopharyngioma suggests the involvement of Rathke’s pouch. The infundibulum is a downward projection of diencephalon; the Rathke’s pouch is an upward elongation of the primitive oral cavity. Rathke’s pouch and the infundibulum develop during the fourth week of gestation and grow towards each other until they unite to form the hypophysis of the pituitary gland during the second month. The remnants of Rathke’s pouch involute into a cleft and disappear completely in normal conditions. In some cases, this Rathke’s cleft remnant can become the site of origin of craniopharyngiomas. Alar plate is related to development of the spinal cord. Isthumus of thyroid is related to thyroglossal duct.
A 45-year-old man presents with sudden onset, uncontrolled, wide flinging movements of his left arm and leg. He is a known diabetic and has not been taking his antihypertensive medications for the last 2 months. He is cognitively intact.
Which of the following is the most likely site of a lesion?
D. The patient described has an acute onset of flinging movements of one side of the body. This is called hemiballism. Movements are usually involuntary, wide amplitude, and irregular with no pattern or rhythm. They commonly involve the arm and leg together; facial involvement has been reported in about half of the cases. Movements are increased with action, decreased with relaxation, and absent during sleep. In some patients the movements can cause physical exhaustion or injury of the affected limb. Hemiballism is considered to be primarily a disorder of the contralateral subthalamic nuclei (STN), but recently lesions outside STN have been demonstrated in patients with hemiballism. It is noted that the hemiballism caused by lesions of the STN is more severe than that caused by lesions elsewhere.
Phineas Gage is a celebrated case in neuropsychiatry. This 25-year-old railroad foreman sustained an extraordinary brain injury after which he had a significant change in his personality characterized by childishness, stubborn, and obstinate behaviour with frequent use of profanities.
Which of the following brain regions was damaged significantly to result in this presentation?
C. The cardinal function of prefrontal cortex is planning and organization of behaviour (executive function) in addition to functions of short-term memory, motor attention, and inhibitory control. The change in Gage’s personality would be consistent with damage to the orbitofrontal cortex of the ventral aspect of his frontal lobe, affecting affect and emotion. A pseudopsychopathic syndrome, characterized by impulsivity and socially inappropriate behaviour, is recognized in orbitofrontal damage. Inferior parietal cortex may play a role in attention and body image function. The primary function of superior temporal cortex is auditory processing. The hippocampus is the seat of episodic memory; lesions can result in amnesia. The hypothalamus is involved in appetitive behaviours such as hunger, thirst, and sex.
A 60-year-old man presents with a 4-week history of right foot pain and sensory loss. The GP prescribes an analgesic and makes a referral to a neurologist. While awaiting the specialist appointment, the patient develops left-sided wrist drop and weakness of right hand grip. He does not have any autonomic disturbances and appears to be cognitively intact.
The most common cause of the above presentation is:
A. Mononeuritis multiplex is a form of peripheral neuropathy wherein axonal destruction occurs in different sites leading to sensory and motor deficits. The nerves involved are generally multiple and random with no predictability of progression. This acute or subacute involvement of multiple individual nerves may be serial or even simultaneous. It is not a single disease but a syndrome caused by various disorders; often the fi nal common pathway includes vascular damage to neurones. Nearly one-third of cases are idiopathic. The most common identifiable cause in adults is diabetes mellitus, followed by vasculitis syndromes such as polyarteritis nodosa and connective tissue diseases such as rheumatoid arthritis or systemic lupus erythematosus. In children and adolescents, the most common cause of mononeuritis multiplex is connective tissue disease. Mononeuritis multiplex can mimic conversion disorder and present to psychiatric units.
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