Sunday, 27 September 2009

Injury to the Midbrain.

The midbrain is a small structure, which lies just above the Pons at the top of the brainstem. It is comprised of smaller structures called the tectum, the tegmentum' the substantia nigra, and the cerebral penduncles. It contains an important group of cells called the 'red nucleus.' At its top end it is connected to the Thalamus and hypothalamus.

Sensory information is processed by the midbrain on it's way to higher centres such as the thalamus. So the midbrain plays it's part in sensory functions such as in helping to control eye movement, depth perception, in addition to other visual and auditory system functions. The red nucleus and substantia nigra help to control body movement and the substantia nigra produce a neurotransmitter called 'dopamine.' Dopamine is part of the 'reward' system of the brain and is involved in motivation and the formation of the addictive process.

When the midbrain is injured, we see several effects.
  • Loss of pupillary reaction
  • Abnormally shaped pupils.
  • Resting tremor (due to injury to dopamine producing cells)
  • Extreme rigidity, (as opposed to spasticity)
  • Auditory disturbances
  • Parkinson's disease
  • Athetosis
  • Coma (if there is injury to the tegmentum).
Parkinson's disease is produced by degeneration in dopamine producing neurons, whilst athetoid cerebral palsy is caused by injury to the same neurons.

Can the injured Midbrain be treated?

Yes! Like all other areas of the brain the mibrain adapts it's functioning and structure to accommodate the environment in which the individual finds himself. If we can provide the correct developmental environment, this inherent plasticity can be harnessed and the individual's probems may improve. If you would like more information about Snowdrop's treatment programmes for brain injury, visit

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