Sunday, June 18, 2017

Micturition and Neurological diseases


Here, presenting you a detailed description of Pathologies of Bladder in Neurology. I believe this is the best resource on this topic available online for free. :)




1. Cortical or Uninhibited Bladder


a. Due to damage to frontal lobe(as in Dementia, Normal Pressure Hydrocephalus) or paracentral lobule (as in ACA region infarct/aneurysm, Parasaggital Meningiomas).

Note that bladder has bilateral representation in the cortex as well as in the spinal cord. So for any lesion to cause bladder defect, it needs to be bilateral.

b. Socially uninhibited bladder. Patient will pass urine in an inappropriate place or time. This is accompanied with intellectual deterioration and impotency.

c. Precipitancy is present. Patient will pass urine on small stimulus like sound of running water, stroking the skin over medial surface of thigh.

d. Hesitancy is present. Patient has difficulty in initiating urination.

e. Patient will have urgency at low bladder volumes due to detrusor hyperreflexia. So there will be very less urine left in the bladder hence the low risk of UTI in these patients.

f. In this condition, there can be spontaneous evacuation of a large volume of urine especially on standing up.

Note: Pontine Glioma
A rule of thumb, Pons facilitate urination( just as Porn facilitates ejaculation :p) while Mid brain inhibits it. So in case of Pontine Glioma or any other lesion, there will be decreased urine evacuation causing retention of Urine.


2. Spinal Bladder 

   When the lesion is above Sacral segment of Spinal cord, most commonly between T1 and L1

Note that the descending fibers controlling micturition reflex lie adjacent to the corticospinal fibres in the lateral column. So Spinal cord lesions and micturition disturbances go hand in hand. 

a. UMNL type of bladder- Spastic Bladder. The bladder is small, hypertonic and contracted, limiting its capacity to hold urine upto a volume of 250 ml only.

b. UMNL has exaggerated reflexes, this holds true here as well. Patient will pass urine frequently because of exaggerated micturition reflexes. Reflex emptying of bladder may occur without warning as in Cortical bladder. But small volume of urine is evacuated each time.

Why the exaggerated micturition relfex? One reason is because of damage to the descending inhibitory fibres. There is one more reason which is more significant. There is damage to sympathetic outflow from T11 to L2 which relays via the hypogastric plexus and has an inhibitory role. 

c. UMNL has hypertonia. So a spastic bladder will have increased tone in the detrusor muscle leading to high intravesical pressure which in turn increases the risk of Reflux Nephropathy.

d. These patients will have relatively empty bladder because of frequent urination. Hence there will be a low risk of UTI.
e. But there is a trick to the above statement. In any Spinal cord injury, there is a state of Spinal Shock for first few days or weeks. During this state, this patient will present to you as a case of Hypotonic bladder with urinary retention and hence high risk of UTI.

f. Think with me now. This patient is a paraplegic, he cannot feel anything below his umbilicus. So the bladder fullness is not appreciated and intravesical pressure rises may only be indicated by sweating, pallor, flexor spasms and dramatic rises in BP. Some doctors can erroneously diagnose it as Phaeochromocytoma.

g. Evacuation may be incomplete but may improve with practice and sometimes be performed at will, if the bladder is massaged and suprapubic pressure is applied[This condition is known as Detrusor-Sphincter Dyssynergia.], on scratching the belly button or inner surface of thighs.



3. When the lesion is at Sacral level; specifically at S3 level(eg Conus Medullaris Syndrome) or roots(eg Cauda Equina Syndrome) or nerves(eg Diabetic Neuropathy)

a. LMNL type of bladder- Atonic/Hypotonic/Flaccid Bladder

b. Urinary Retention is present. Hence, there is high risk of UTI.

c. Overflow Incontinence is present. Understand that there is too much vol of urine in the bladder which mechanically forces open the internal urethral sphincter causing Dribbling of drops of urine. Sometimes called Continual Dribbling Incontinence.

d. It may be associated with perineal numbness and impotency.

Now let us take three patients A, B and C, all having Hypotonic bladder.

Patient A has motor paralytic bladder, that means there is damage to the motor control of the bladder. He/She may have a history of Pelvic surgery or Pelvic trauma. This condition is diagnosed early since its a very painful condition. Pain being transmitted through the sensory component of sympathetic autonomic nerve fibers.

Patient B has sensory paralytic bladder, that means that is devoid of all the afferent connections. This patient is most probably a diabetic with a poorly controlled blood glucose. It can also occur in several other disorders like Tabes Dorsalis, Subacute Combined Degeneration and Multiple Sclerosis.  Since there is no sensory supply, there is no pain. So this condition is diagnosed very late and the patient usually presents with complaints of UTI.

Patient C has Autonomous Bladder, that means both sensory and motor components are lost. This happens in Cauda Equina Syndrome, after Pelvic Surgery or Trauma, Pelvic Malignant disease, Spina Bifida and rarely disc lesions. This patient presents in a similar fashion to Patient B.

Patients of Hypotonic bladder should be taught self-catheterization.

Few questions for readers-
1>Why is there an instant desire to pass urine on getting up in the morning?

2>Suppose that you really want to pass urine, you are having a strong urge but you are in a bus or something and you have to hold on. What maneuvers can you do to reduce this urge?

3> What is Micturition Syncope?


That's all!

-VM


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