#14114 - Lesions - Neuroscience 1

Lesions

Spinal cord injuries

Complete cord transection syndrome:

-Complete loss of all sensibility and voluntary movement below level of the lesion-can be caused by fracture, dislocation of vertebral column by a bullet or stab wound or by expanding tumour

Symptoms:

-Bilateral lower motor neuron paralysis, muscular atrophy in segment of lesion – due to damage of motor neurons in ventral horns

-Bilateral spastic paralysis below the level of lesion- A bilateral Babinski sign is present and depending on level of the segment of spinal cord damaged –due to interruption of corticospinal tracts

-Bilateral loss of all sensations below the level of lesion-loss of tactile discrimination and vibratory and proprioceptive sensations due to bilateral destruction of ascending tracts in posterior white columns. Due to damage to lateral and anterior spinothalamic tracts

-Bladder and bowel functions no longer under voluntary control-all descending autonomic fibres are destroyed

Anterior cord syndrome

-Cord contusion during ventebral fracture, from injury to anterior spinal artery- ischaemia of the cord

Symptoms:

-Bilateral lower motor neuron paralysis in segment of lesion and muscular atrophy- due to damage in neurons in anterior grey coloumns

-Bilateral spastic paralysis by interruption of anterior corticospinal tracts on both sides of the cord

-bilateral losss of pain, temperature, light touch and pressure sensations

Brown sequard syndrome

Hemisection of the spinal cord (only Right half or left half is severed), so all tracts ascending and descending coursing through the level of lesion are servered

Symptoms

-Lower motorneurons ipsilateral to and at the level of lesion will be damaged- ispsilateral lower motorneuron paralysis at level of lesion

-Corticospinal tract (upper motorneurons) will be severed the individual will exibit ipsilateral loss of motor function below level of lesion followed by spastic paralysis

-Anterolateral system (spinothalamic, spinoreticular, spinomesencephalic, spinotectal and spinohyothlamaic fibres) will be severed- contralateral loss of pain and temperature sensation beginning one or two segments below lesion and nondiscriminative touch beginning three/four segments below level of lesion

-Dorsal coloumn pathway is also severed- ipsilateral loss of discriminative touch and vibratotry sensation.

-Loss of proprioception- if lesion affects lower limbs-difficulty in maintaining balance and feet are closely approximated when eyes are closed

Loss of astereognosis (inability to know solids)- unable to identify shape and form of an object such as a fork following manual examination with eyes closed

-Loss of two point discrimination

Syringomyelia

One reason why these symptoms may arise could be due to Syringomyelia. In this disease a cyst, known as a syrinx, forms within the spinal cord and overtime elongates. It occurs when excess CSF forms within the central canal which causes fluid to burst into the surrounding white matter and leads to the formation of cysts. These cysts result in lesions within the centre of the spinal cord which damages the decussating 2^nd order axons in the spinal cord which carry pain and thermal stimuli from the delta alpha and C fibres. As the damage occurs in the centre of the...