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Posts Tagged ‘Spinal cord injury’

‘Cyborg’ spinal implant could help paralysed walk again

February 8, 2015 Leave a comment

It might seem like science fiction but a new implant which attaches directly to the spine could help paralysed people walk again

The implant is so effective because it mimics the soft tissue around the spine so that the body does not reject its presence.

Paralysed patients have been given new hope of recovery after rats with severe spinal injuries walked again through a ‘groundbreaking’ new cyborg-style implant.

In technology which could have come straight out of a science fiction novel or Hollywood movie, French scientists have created a thin prosthetic ribbon, embedded with electrodes, which lies along the spinal cord and delivers electrical impulses and drugs.

The prosthetic, described by British experts as ‘quite remarkable’, is soft enough to bend with tissue surrounding the backbone to avoid discomfort.

Paralysed rats who were fitted with the implant were able to walk on their own again after just a few weeks of training.

Researchers at the Ecole Polytechnique Fédérale de Lausanne are hoping to move to clinical trials in humans soon. They believe that a device could last 10 years in humans before needing to be replaced.

The implant, called ‘e-Dura’, is so effective because it mimics the soft tissue around the spine – known as the dura mater – so that the body does not reject its presence.

“Our e-Dura implant can remain for a long period of time on the spinal cord or cortex,” said Professor Stéphanie Lacour.

“This opens up new therapeutic possibilities for patients suffering from neurological trauma or disorders, particularly individuals who have become paralyzed following spinal cord injury.”

Previous experiments had shown that chemicals and electrodes implanted in the spine could take on the role of the brain and stimulate nerves, causing the rats’ legs to move involuntarily when they were placed on a treadmill.

But this is the first study to show a simple gadget can help rats walk again and be tolerated by the body.

Scientists have struggled to find a device which will sit next to the spine or brain because both are surrounded by a protective envelope of tissue which the hard surface of implants can rub against, causing inflammation and scar tissue

The electronic ribbon is placed directly onto the spinal cord.

However the new gadget is flexible and stretchy enough that it can be placed directly onto the spinal cord. It closely imitates the mechanical properties of living tissue, and can simultaneously deliver electric impulses and drugs which activate cells.

The implant is made of silicon and covered with gold electric conducting tracks that can be pulled and stretched. The electrodes are made of silicon and platinum microbeads which can also bend in any direction without breaking.

Writing in the journal Science, where the results were published, science writer Robert Service said: “Soft flexible nerves connected to unyielding silicon and metal – the combination has spawned many a Hollywood cyborg.

“The implants Lacour’s team created still have to be wired to the outside world to operate, but she and her colleagues are designing wireless versions of the technology. Watch out, Hollywood, reality is catching up.”

The research was praised by British scientists.

“The work described here is a groundbreaking achievement of technology, which could open a door to a new era in treatment of neuronal damage,” said Dr Duško Ilić, Reader in Stem Cell Science at King’s College London.

“Until now, the most advanced prostheses in intimate contact with the spinal cord caused quite substantial damage to tissue in just one week due to their stiffness.

“There is still a long way to go before we may see any practical use of such neuroprostheses in humans. But it may be that it is something that could potentially be developed for use in humans in the foreseeable future.”

Prof John Hunt, Head of Unit of Clinical Engineering, University of Liverpool, added: “This study in rats is an interesting one and it could have the potential to be quite promising in terms of being applicable to people with spinal injuries.”

The implant has been primarily tested in cases of spinal cord injury in paralyzed rats but researchers believe it could eventually be used in epilepsy, Parkinson’s disease and pain management.

The scientists are planning to move towards clinical trials in humans within the next few years.

Additional Link:

NCBI – ‘Bionic’ spinal implant helped paralysed rats walk.

 

The research was published in the journal Science.

The above story is reprinted from materials provided by The Telegraph.

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Descending Tracts

February 17, 2012 Leave a comment

Descending tracts have three neurons:

1.   1st order neurons (UMN): cell bodies are in the cerebral cortex and other supra spinal areas

2.   2nd order neurons: short and situated in the anterior grey column of the spinal cord

3.  3rd  order neuron (LMN): situated in the anterior grey column and innervate the skeletal muscles through anterior roots of the spinal nerves

Corticospinal tract: rapid, skilled and voluntary movements

1st order neuron

Axons arise from the pyramidal cells of the cerebral  cortex  (situated  in  the  5th   layer),  2/3 from the pre central gyrus and 1/3 from the post central gyrus:

1. 1/3 of fibers arise from the 1stry motor  cortex (Area 4)

2. 1/3 of fibers arise from the 2ndry motor cortex (Area 6)

3. 1/3 of fibers arise from the parietal lobe

(Area 1, 2 and 3).

Descending fibers converge in the corona radiata and  pass  though  the   posterior  limb  of  the internal capsule; organization of fibers within the internal capsule:

1. close to genu (medial): concerned with the cervical parts of the body

2. away from the genu (lateral): concerned with the lower extremity.

The tract then passes through the middle 3/5 of the basis pedunculi of the midbrain; organization of fibers in the midbrain:

    1. medially: cervical parts of the body
    2. laterally: lower limbs.

When the tract enters the pons, it’s broken into many bundles by the transverse pontocerebellar fibers. In the medulla oblongata, the bundles group together to form the pyramids. At the junction of the MO and the spinal cord, most fibers cross the midline at the decussation of the pyramids and enter the lateral white column of the spinal cord to form the lateral corticospinal tract (LCST). LCST descends length of the spinal cord and terminates in the anterior grey column of all the spinal segments.

The fibers which didn’t cross, descend in the anterior white column of the spinal cord as the anterior corticospinal tract (ACST). Fibers of the ACST eventually cross and terminate in the anterior grey column of the spinal cord segments in the cervical and upper thoracic regions.

2nd order neuron:

It’s an internuncial neuron.

3rd order neuron:

It’s a alpha or gamma motor neuron.

To read more click on this link to the full article: Descending Tracts

Ascending Tracts

February 10, 2012 Leave a comment

Introduction

They are located in the white matter and conduct afferent information (may or may not reach consciousness). There are two types of information:

  1. Exteroceptive : originates from outside the body (pain, temperature and touch
  2. Proprioceptive : originates from inside the body (from muscles and joints)

Normally there are three neurons in an ascending pathway:

  1. 1st order neuron: cell body is in the posterior root ganglion
  2. 2nd  order neuron: decussates (crosses to the opposite side) and ascends to a higher level of the    CNS
  3. 3rd neuron: located in the thalamus and passes to a sensory region of the cortex

Pain and temperature pathway: lateral spinothalmic tract

1st order neuron

Peripheral process extends to skin or other tissues and ends as free nerve endings (receptors). Cell body is situated in the posterior root ganglion. Central process extends into the posterior grey column and synapses with the 2nd order neuron.

2nd order neuron

The axon crosses obliquely to the opposite side in the anterior grey and white commissures within one spinal segment of the cord. It ascends in the contralateral white column as the lateral spinothalamic tract (LSTT).

As the LSTT ascends through the spinal cord new fibers are added to the anteromedial aspect of the tract (sacral fibers are lateral and cervical fibers are medial). The fibers carrying pain are situated anterior to those conducting temperature.

As the LSTT ascends through the medulla oblongata,  it’s  joined  by  the  anterior spinothalamic tract and the spinotectal tract and forms the spinal lemniscus. Spinal lemniscus ascends through the pons and the mid brain.

Fibers of the LSTT end by synapsing with the 3rd order  neurons  in  the  ventral  posterolateral nucleus  of  the  thalamus  (here  crude  pain  and temperature sensations are appreciated).

3rd order neuron

Axons pass through the posterior limb of the internal capsule and corona radiata  to reach the somatosensory  area  in  the  post  central  gyrus  of  the  cerebral  cortex.  From  here  information is transmitted to other regions of the cerebral cortex to be used by motor areas. The role of the cerebral  cortex  is  interpreting  the  quality  of  the  sensory  information  at  the  level  of  the consciousness.

Light (crude) touch and pressure pathway: anterior spinothalamic tract (ASTT)

1st order neuron

It is similar to the pain and temperature pathway.

2nd order neuron

The axon crosses obliquely to the opposite side in the anterior grey and white commissures within several spinal segments. It ascends in the contralateral white column as the anterior spinothalamic tract (ASTT). As the ASTT ascends through the spinal cord new fibers are added to the anteromedial aspect of the tract (sacral fibers are lateral and cervical fibers are medial).

As the ASTT ascends through the medulla oblongata, it’s joined by the lateral spinothalamic tract and the spinotectal tract and forms the spinal lemniscus. Spinal lemniscus ascends through the pons and the midbrain. Fibers of the ASTT end by synapsing with the 3rd order neurons in the ventral posterolateral nucleus of the thalamus (here crude awareness of touch and pressure sensations are appreciated).

3rd order neuron

Axons pass through the posterior limb of the internal capsule and corona radiata to reach the somatosensory area in the post central gyrus of the cerebral cortex. The sensations can be crudely localized. Very little discrimination is possible.

To read more click on this link to the full article: Ascending Tracts (pdf).