Neuroanatomy
Dr Raymond Chang
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Osmotic Demyelination Syndrome
This is a set of cranial MRIs from a patient with osmotic demyelination syndrome, formerly called central pontine myelinolysis. Osmotic demyelination syndrome occurs when wide fluxes in serum sodium levels are induced by too rapid correction of hyponatremia. Oligodendrocytes, which forms the myelin sheaths, are particularly vulnerable to osmotic changes. If the osmotic stress is…
Heel-shin Test
In this video, the patient exhibits a positive heel-shin test on the right side. Compared to the left (normal) side, the right lower limb is seen to be rather clumsy. The heel-shin test is a test to screen for ipsilateral cerebellar function. Once again, clear instructions are required for this test, and you could see…
Sixth Nerve Palsy
In this patient, there is a mild esotropia on neutral gaze as the left eye is slightly deviated medially. There is impaired left eye abduction resulting in diplopia when the patient is instructed to look towards the left. Discussion of the sign Abduction of the eye is controlled by the lateral rectus muscle, which is…
Assessing the Level of Consciousness
Dr Gilberto Leung and Dr Gary Lau Subtitles in English for this video can be displayed by clicking on (first button on the bottom right hand corner of the video). Our level of consciousness is governed by our cerebral cortex as well as the subcortical ascending reticular formation. Patients with normal consciousness have a high level…
Intention Tremor
Intention tremor can be elicited by the finger-nose test. In normal patients, the movements between the physician’s finger and patient’s nose should be smooth, but adjustment is allowed according to the patient’s upper limb power. This man has intention tremor and impaired finger-nose test on the right side, whilst the left side is normal. Discussion on intention…
Horizontal Nystagmus
In the first video, the patient has both horizontal nystagmus and vertical “down-beat” nystagmus. In the second video, the patient has a torsional nystagmus when looking to her right hand side. Discussion of the sign Nystagmus is defined as a rhythmic oscillation of the eyes. It usually consists of a slow drifting phase in one direction and a…