clinical neurology for medical students
TRANSCRIPT
Introduction to clinical neurology
Osama a. ragab
Neurology md
2016
Organization of the nervous system
Frontal – motor control of the opposite side ofthe body, insight and control of emotions and, inthe dominant hemisphere, output of speech.
Temporal – memory and emotions and, in thedominant hemisphere, comprehension of speech.
Parietal – sensation of the opposite side of thebody and appreciation of space, especially in thenon-dominant hemisphere.
Occipital – appreciation of vision.
The basal ganglia are interconnected deepnuclei including the putamen, caudate,globus pallidum and substantia nigra withcomplicated interrelations.
They are involved in the integration ofmotor and sensory inputs. when things gowrong, they produce clinical syndromes ofinvoluntary movement.
The cerebellum coordinates movement andis important in the control of balance andposture.
The cerebellar hemispheres controlcoordination on the same side of the body.The central cerebellar structures areimportant in gait and sitting balance.
The brain stem contains nuclei, including thereticular formation, which maintainsconsciousness, and those for the cranial nerves (3–12), and the large white matter tracts running fromthe spinal cord to more central structures and viceversa.
The descending motor tract, the corticospinaltract, mostly crosses over (decussates) in thepyramids in the medulla. The ascending dorsalcolumn crosses in the medulla.
The fact that these tracts cross in the brain stem ishelpful in localization of any lesion. A brain stemlesion can produce a cranial nerve lesion on oneside and limb signs on the other side
Spinal cord is made up of 31segments which areregionally subdivided fromabove downwards asfollows—
Cervical – 8
Thoracic – 12
Lumbar – 5
Sacral – 5
Coccygeal – 1
The nerve roots leave the spinal canal through theirexit foramina. In the lumbar spine the nerve rootsfrom the lower end of the spinal cord form the caudaequina before leaving the lumbosacral spinal canal.
The roots combine in the cervical and lumbosacralregions to form the brachial plexus and lumbosacralplexus.
The brachial and lumbosacral plexuses then divideinto named nerves.
Stimulation of the motor nerves will then lead to therelease of acetylcholine at the neuromuscularjunction, which binds to acetylcholine receptors,leading to muscle contraction.
The autonomic nervous system t isclassified into two divisions:
Sympathetic ‘alarm’ system, whicharises from the spinal segments T1 toL2.
Parasympathetic ‘holiday’ system,which arises from the brain stem(associated with cranial nerves 3, 7and 9) and the spinal segments S2–4.
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• positive (parathesia, ,. dysthesia ,. Pain, unpleasant sensation indicatingongoing tissue destruction. Allydonia. Hyperalgesia painful stimuliproduce more pain.
• Negative sensory complaint such as hypothesia , anesthesia or analgesia .
• Sensory loss may be associative.or dissociative .
• It may affect one side of body , both lower limb , face only, one dermatomeor overlapping dermatomes, jacket distribution, gloves and stocking andpatch of sensory ( leprosy ).
• Urinary ( urge– incontinence , hesitancy---- retention).
• Rectal complaint such as constipation or incontinence .
• Sexual dysfunction .
• Cognitive dysfunctions .
• Dyscalculia, Dysphasia, dyslexia, agnosia and apraxia.
• Alterations of level of consciousness .
• Seziures
• fever (infection), vomiting ( increased intracranial tension) , rash(HZ, meningitis) ,abdominal pain ( epilepsy, porphyria , migraine )headache , skeletal deformities ( long standing neuropathy) , skin andoral ulcers (vasculitis).
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