LUMBAR PUNCTURE (SPINAL TAP)

LUMBAR PUNCTURE (SPINAL TAP)

 

INTRODUCTION: It is an important element to have a detailed view of the procedure known as Lumbar puncture which is also known as the Spinal Tap.

It is mostly used as a diagnostic procedure by which a sample of CSF can be obtained, (which is known as the Cerebrospinal Fluid, the fluid found in the brain and spinal cord.) which is used for bacterial or microscopic examination in the case of meningitis, as well as providing a way for injecting drugs like in the case of chemotherapy. Anesthetic drugs and antibiotics are also injected into the Cerebrospinal fluid via the Spinal tap. This procedure also provides a means of measuring the pressure in the Cerebrospinal fluid with the help of a manometer.

Cerebrospinal Fluid is a clear colorless fluid produced by the choroid plexus and assisted by the ependymal cells. It contains inorganic salts like chloride, glucose few lymphocyte cells and trace amounts of protein. The pressure range of cerebrospinal fluid measured by the manometer is said to be about 60 – 150mm water and the rate of the production of cerebrospinal fluid is 0.5ml/min. (Snells Neuroanatomy)

The basic function of cerebrospinal fluid is to cushion or protect the brain from any mechanical trauma. It also provides buoyancy to the brain due to the increased density of the cerebrospinal fluid. The fluid also acts as a source of nourishment for the underlying nervous tissue and also acts as a pathway for the pineal secretions from the pituitary gland.

Method: The patient, on whom the lumbar puncture is to be performed should lie in a lateral Recumbent position i.e. on the side or even in a prone or sitting position depending on the preference of the health caregiver or a clinician. The vertebral column should be well flexed and the lamina in the lumbar region should be opened to the maximum.

There is an imaginary line which is obtained by joining the highest points on the iliac crests and when joined passes over the fourth lumbar vertebrae. From L3 to the lower border of the S2 vertebrae the subarachnoid space filled with cerebrospinal fluid is accessible and safe to penetrate as the spinal cord in an adult already terminates at the level of L1 and L2 vertebrae, thus making the lumbar region an ideal site to perform the Spinal tap.

The physician then uses a careful aseptic technique and the patient is provided with local anesthesia. The lumbar puncture needle that is the Quincke spinal needles 22G which may be of size 1.5 for infants and newborn, 2.5 for children and 3.5 for adults, fitted with a stylet is passed through anatomical structures like the skin, superficial fascia, Supraspinous ligament, Interspinous ligament, Ligamentum flavum, areolar tissue (which contains the internal vertebral venous plexus), Dura mater and the Arachnoid mater, ending in the subarachnoid space which contains the cerebrospinal fluid. It is from here that we are able to aspirate a sample of cerebrospinal fluid. The needle will pass through these structures to a depth of 1inch (2.5cm) in a normal adult and less in a child, however, in the case of an obese patient a depth of 4 inches is required.

When the stylet is withdrawn and if few drops of blood are seen, it is then due to the fact that the needle has only entered the internal vertebral plexus and might still be in the areolar tissue. The patient would experience a fleeting discomfort in a muscle or a dermatome if the nerve roots of the cauda equina were stimulated. If the needle is in the lumbar cistern and the stylet is withdrawn the cerebrospinal fluid would start flowing and escapes at a rate of approximately one drop per second. The cerebrospinal fluid’s normal pressure is about to 60 -150mm of water and if the subarachnoid pressure is high then the fluid would escape out as a jet.

Anesthetic drugs are also given in the extradural space and in the subarachnoid space in order to anesthetize the nerve roots of the lumbar and sacral area, which is helpful in operations of the pelvic and the leg. The patient is advised to be in an erect position during these surgeries as if the patient is in a recumbent position then the anesthesia would be only effective unilaterally and if the patient is in a head-down position the anesthetic could pass cranially and affect respiration.

Some of the complications include Post-dural puncture headache, infection, cerebral herniation, bleeding and back pain. It is contraindicated when there is an increased intracranial pressure, thrombocytopenia or any brain abscess.

Types of equipment used:

Sterile gloves

1% lidocaine solution

22G or 25G needle

5ml disposable syringe

Sterile drape

Spinal needle with stylet

Manometer with 3 way stopcock

A labeled sterile specimen container

Sterile bandage

Story of Multiple Epiphyseal Dysplasia

Story of Multiple Epiphyseal Dysplasia

 

A very rare disease which you will misdiagnose most of the times.

Let’s me introduce you to this skeletal system disorder called Multiple Epiphyseal Dysplasia.

I have a Friend of mine who has a deformity in both of her legs and being a medic I had a very simple diagnosis in my mind which of course I never discussed with her. But suddenly a few days back she was very depressed and she wanted my help so she said to me. Hey, can you suggest me some simple ways to prevent it from getting more deteriorated?

That was the moment I was stunned and I started to go into the depth of my ignorance.

In a curious manner, I asked her what is the thing that you feel is getting worse. She replied to me that now she cannot sit on a motorbike because the distance between her legs was getting lesser with time and she has a waddling gait. She also said that she cannot even squat and many of the body postures which we do so subconsciously aren’t possible for her and is the reason for her depression. She added that her younger sister had even worse symptoms which also included pain along with postural defects and bowed legs.

Later I discovered that it was a disease which ran in her family and they inherited it from their mother who also had the same disease. So it was her mother and my friend with her younger sister and a younger brother who had the same condition known as Multiple Epiphyseal Dysplasia.

It is a rare disease so not many physicians know about it. People suffering from this disease have very fewer chances of getting a proper treatment in time as it is apparent only after 10-12 years that this becomes physically appreciable in the manner of bowing of legs towards outside and associated knock knees most of the times.

The diagnosis of this condition is very difficult as it requires sophisticated multidisciplinary setups with a facility of Genetic and Molecular Testing.

There are not many treatment options available as many it is claimed that the disease cannot be cured completely but only a few modifications can be made surgically to avoid the daily life problems related to sitting and posturing. Surgeries might include arthroplasty and joint replacement to correct the deformity.

The best approach is to reduce the effects of deformity by regular physiotherapy, weight control, and Psychological Counseling.

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