Hemisection of the spinal cord (Brown
Mr. Y, 40 years old, was in a traffic accident and
was taken to the Emergency unit. The patient
was still conscious but could not walk unaided.
Paralysis cover his right arm and legs. On
examination, a hematoma was found on the
back of his neck. He could not feel any sensation
of pain on his left starting from his foot up to the
base of his neck. Physical examination revealed
right biceps reflex and right patellar reflex were
negative. The pupil of his left eye was
constricted, with ptosis and enophthalmus.
Paralysis of the right side of the body
Loss of pain sensation of the left side of the
body, starting from the neck down.
Right biceps reflex and right patellar reflex
Pupillary constriction, ptosis, and
enophthalmus of the right eye
Where is the probable site of
lesion in the nervous system??
According to the dermatom area, the patient
got loss of sensation up to segment C3 of
dermatom (Base of the neck is C2-3) .Thus,
the probale site of the lesion is on C3 or
bellow C3 segment of the spinal cord.
Since the paralysis is on the right side, the
lesion must be on the right section of the
spinal cord (look at the picture)
The injured tracts :
from the left side of
dan cuneatus Fasciculus gracilis
from the right side of
Lower motor neuron in
the area of the lesion eg.
C5-6 that innervate
Corticospinal tract (UMN
axon) that will end in UMN
spinal cord segment
bellow the lesion
LMN paralysis : LMN in the spinal cord at the
level of the lesion (C3,4,5,6..)
C3-4 innervate diaphragm breathing difficulty
C5-6 innervate biceps flaccid paralysis, reflex (-)
UMN paralysis : affected the corticospinal tract
(UMN axons) that will end in the spinal cord
segment bellow the lesion spastic paralysis.
Patellar reflex :
Negative : due to spinal shock (0-1 day)
positive: 1 – 7 day
Hyperreflex : 1-4 week spasticity
Two point discrimination (using
Left side of the body can differentiate two
Right side of the body cannot differentiate
Horner syndrome :
Lesion on sympathetic fibers which innervate
the head region.
Preganglionic neuron : intermediolateral horn of the
T1 segment of the spinal cord
Postganglionics neuron: superior cervical ganglion
Pupillary constriction: due to paralysis of the
dilator muscle of the eye
Pseudoptosis : due to paralysis of the levator
palpebra superior muscle (smooth muscle part)
Enophthalmus: due to narrowing of the
palpebral fissure (not true enophthalmus)