Case history

A 66-year-old woman presented unrousable from sleep one Sunday morning, having been well the previous evening. She remained sleepy for several hours, opening her eyes to verbal commands but remaining vague and disorientated with difficulty forming sentences. A CT scan of the head was reported as normal. She improved during the day and was discharged after a brief admission.

Over the next 5 days, her husband reported that she was not herself. She had clear word-finding difficulty, more pronounced when speaking English rather than her native Dutch. She was unsteady and veered to the right when walking. She would sleep for long periods and had difficulty reading. At no time did she have neck pain.

On examination following readmission 24 h later, she was in sinus rhythm, normotensive, with normal heart sounds but no carotid bruits. She was orientated but sleepy. She had a subtle expressive dysphasia with word-finding difficulty. Her memory was grossly intact. The amplitude and velocity of vertical saccades was reduced. She had no weakness, sensory loss, or pyramidal signs in her limbs, but her gait was ataxic.

A CT scan of head (figure 1) showed low density in the medial left thalamus, consistent with an infarct. Routine blood tests, chest X-ray, 12-lead ECG and Doppler scan of the extracranial carotid and vertebral arteries were normal. A transthoracic echocardiogram found a patent foramen ovale, with right-to-left shunt.

We prescribed antiplatelet therapy and a statin. She gradually improved but 3 months later still had occasional word finding difficulty and, by choice, has a short sleep in the afternoon.

We diagnosed a paramedian thalamic infarction, probably due to an embolus from a proximal embolic source. She subsequently underwent closure of her patent foramen ovale.

Thalamic structure and function—a ‘rule of 4’

The thalamus lies between the midbrain and forebrain. It …