Sunday, May 28, 2017

Lesions of the Central Nervous System.


Hello everybody!

So today we'll review a series of lesions and their presentation starting from the cortex till the spinal cord.

Will try and include as many lesions as I can without making it redundant or boring.

To start with.

1)Disorders of the Meninges and Ventricular System.

Many conditions can affect the meninges, like infections, neoplasia, sarcoidosis.The most common being infections.

Some meningeal infections may be extremely indolent and lack the classical signs associated with infection.
Chronic meningitis can also present as dementia or AMS.
Abnormalities of the ventricular system can occur due to congenital anomalies, such as aqueductal stenosis leading to dilatation of the ventricular system and may cause increased head circumference in children.
In adults, acquired conditions, such as normal pressure hydrocephalus usually present with evidence of increased intracranial pressure or with dementia, AMS, gait problems,difficulty with bladder control. The classic triad of Normal pressure hydrocephalus is - WET WHACKY WOBBLY.

2)Cerebral Hemisphere Disorders. Characteristic of unilateral hemispheric pathology is a “hemi” deficit.
Hemisensory loss,
Hemiparesis,
Hemianopsia,
Hemiseizures.

Other manifestations are hyperreflexia and pathologic reflexes.

Disease affecting the cerebral cortex behave differently from disease of subcortical structures.

Cortical involvement:
Aphasia,
Apraxia,
Astereognosis,
Impaired two-point discrimination, Memory loss,
Cognitive defects,
Focal seizures, or other abnormalities that reflect integrative role of the cortex.

Dominant hemisphere involvement:
Language dysfunction in the form of aphasia, alexia, or agraphia. 

Non dominant hemisphere involvement:
Higher cortical function disturbances involving functions other than language, such as apraxia.

Subcortical structures :
The clinical picture includes the hemidistribution of dysfunction but lacks those elements that are typically cortical (e.g., language disturbance, apraxia, seizures, dementia).

Certain processes involve wide areas of the cerebrum, causing diffuse dysfunction.

3) Basal Ganglia Disorders:
Diseases of the basal ganglia cause movement disorders such as Parkinson’s disease (PD) or Huntington's Disease. Movement disorders may be hypokinetic or hyperkinetic, referring to whether movement is in general decreased or increased.
PD causes bradykinesia and rigidity. Huntington’s disease, in contrast, causes increased movements, which are involuntary and beyond the patient’s control (chorea).  Tremor is a frequent accompaniment of basal ganglia disease.

4)Brainstem Disease: (So I have a  separate blog on these do check them out,where I have enlisted individual syndromes.)

The classic distinguishing feature of brainstem pathology is that deficits are “crossed,” with cranial nerve dysfunction on one side and a motor or sensory deficit on the opposite side.

There are often symptoms reflecting  dysfunction of other posterior fossa structures, such as vertigo, ataxia, dysphagia, nausea - vomiting, and abnormal eye movements.

Unless the process has impaired the reticular activating system, patients are normal, mentally awake, alert, able to converse (though perhaps dysarthric), not confused, and not aphasic. 

DeepTendon Reflexes are usually hyperactive with accompanying pathologic reflexes in the involved extremities; pain is rare untill Thalamus is involved and sphincter dysfunction occurs only if there is bilateral involvement.

5) Cranial Neuropathy Disease :
Selectively involve one, or more than one, cranial nerve.
The long tract abnormalities, vertigo, ataxia, and similar symptoms and findings that are otherwise characteristic of intrinsic brainstem disease are lacking.

Common cranial neuropathies include Optic neuropathy due to MS,
Third nerve palsy due to aneurysm
Bell’s palsy.
Involvement of more than one nerve occurs in conditions such as Lyme disease, sarcoidosis, and lesions involving the cavernous sinus

6)Cerebellar Disease:
Leads to combinations of tremor, incoordination, difficulty walking, dysarthria, and nystagmus, depending on the parts of the cerebellum involved. 

There is no weakness, sensory loss, pain, hyperreflexia, pathologic reflexes, sphincter dyscontrol, or abnormalities of higher cortical function.

Cerebellar abnormalities resulting​ from dysfunction of the cerebellar connections in the brainstem, usually are accompanied by other brainstem signs.

7)Spinal cord disorders:
Produce characteristic patterns of clinical abnormalities, with motor and sensory deficits in a certain distribution.

In addition to weakness below the level of the lesion, patients with spinal cord lesions also have paresthesias, numbness, tingling, and sensory loss with a discrete sensory level, usually on the trunk.

The pattern of weakness is typically more localizing than sensory abnormalities in lesions of the cervical spinal cord, while demonstration of a sensory level on the trunk is more helpful in localizing lesions of the thoracic cord.

Some important findings depicting the syndromes are :

Dorsal cord syndrome : Loss of position and vibratory sensation in the feet with preserved ankle jerks.

Central cord Syndrome (syringomyelia) :
Bilateral segmental sensory loss (i.e., sensory loss in the hands and forearms), not in a peripheral nerve distribution, with normal sensation in the legs and trunk and in the upper arms and neck.

Thoracic Cord Syndrome : Bilateral loss of position and vibratory sensation in the feet with a definite level of pinprick loss on the abdomen or chest.

Brown-Séquard syndrome : Loss of pinprick sensation on one side of the body with loss of position and vibration sensation on the other.

Intramedullary lesion or anterior extramedullary compression :
Loss of pinprick sensation over the legs and trunk with normal sensation in the perianal area.

Conus medullaris or L5–S1 cauda  equina lesion:
Loss of pinprick sensation in the perianal area and in the upper part of both posterior thighs.

Anterior Cord Syndrome :
Loss of pinprick sensation on the legs and trunk with normal position and vibration sense in the toes and fingers.

Phew😅 that was alot.
I hope this was helpful.
If you have any doubts or you need a detailed explanation of some part, do let me know.

Let's learn Together!
-Medha.

8 comments:

  1. Thank you so much Medha . This is enough for now,but I will ask u if i get any doubts.
    Can you suggest me any book where i can find these all

    ReplyDelete
  2. You are most welcome!
    Read a book on Neurological examination by Bickerstaff. It's more than enough for undergraduate level.
    Also Kundu and PJ Mehta.

    ReplyDelete
  3. Okay I will read from those.Thank u😃

    ReplyDelete
  4. Really awesome explanation. I would like to know the difference between lesions of pons and medulla.

    ReplyDelete
    Replies
    1. Wokay, différence as to Which structures are affected and Which aren't?

      Delete
  5. Thank you! Could you possibly post the link to Brainstem lesions? I can't seem to find it

    ReplyDelete
    Replies
    1. Brainstem Syndromes! http://www.medicowesome.com/2017/03/brainstem-syndromes.html

      Delete
    2. It's in parts so check em all out.😊

      Delete

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