Neuroanatomy Draw It To Know It

122 Neuroanatomy: Draw It to Know It

Spinal Cord Disorders (Cont.)

Case IV

Patient presents with a few-month course of progressive
burning pain across the shoulders. Exam reveals weak-
ness of the upper extremities; absent biceps refl exes with
hyperrefl exia of lower extremities; pathologic (ie, posi-
tive) Babinski’s; absent pain/temperature sensation
across the upper chest and limbs with preserved vibra-
tion/proprioception sensation.
Show that the dissociation of loss of pain/temperature
sensation with preserved vibration/proprioception sen-
sation in a suspended sensory level suggests damage to the
crossing anterolateral system fi bers. Show that the loss of
strength and arefl exia of the upper limbs in that same seg-
ment suggests bilateral anterior motor horn damage.

Indicate that this constellation of defi cits suggests a

central cord syndrome, oft en a syringomyelia.

Syringomyelia is a fl uid-fi lled cavity within the

spinal cord, which may be limited to a dilatation of the

central canal, may extend outside of the central canal, or

may be separate from the central canal, entirely. It causes

lower motor neuron signs at the level of the lesion,

impaired pain/temperature sensation but preserved

vibration/proprioception in a segmental distribution

(classically, in a cape-like distribution across the arms

and upper trunk): a so-called suspended sensory level,

and upper motor neuron signs below the level of the

lesion.^18 – 21

Case V

Patient presents with a few-month course of trunk and
lower limb sensory dysesthesias. Exam reveals hyperre-
fl exia throughout except for absent ankle jerks; patho-
logic (ie, positive) Babinski’s; loss of vibration/
proprioception sensation in the lower extremities with
preserved pain/temperature sensation; and mild, diff use
lower extremity weakness.
Show that the loss of vibration/proprioception sensa-
tion with preserved pain/temperature sensation suggests
posterior column involvement. Th en, show that the diff use
motor weakness is due to corticospinal tract involvement.

Indicate that this combination of defi cits is oft en

found in subacute combined degeneration due to vitamin

B12 defi ciency. Subacute combined degeneration aff ects

the posterior and lateral columns. Although not men-

tioned, gait ataxia is oft en present in this disorder and

may be due to the profound vibration/proprioception

sensory loss or due to posterior spinocerebellar tract

involvement from lateral column patholog y. B12 defi -

ciency also oft en causes a superimposed neuropathy,

which explains the absent ankle jerks.^18 – 21 , 23 , 24

Case VI ( Advanced )

Patient presents with longstanding gait disturbance and
weakness. Exam shows lower extremity arefl exia with
preserved upper extremity refl exes; pathologic (ie, posi-
tive) Babinski’s; profound ataxia; vibration/propriocep-
tion sensory loss out of proportion to pain/temperature
sensory loss; and motor weakness of the upper and lower
extremities.
First, show that the mixed refl ex pattern in the pres-
ence of pathologic Babinski’s suggests a mixed upper and
lower motor neuron disease pattern with patholog y of
the dorsal nerve roots and dorsal horns. Th en, show that

the vibration/proprioception sensory loss with preserved

pain/temperature sensation suggests posterior column

involvement. Next, show that the profound ataxia sug-

gests spinocerebellar tract involvement. And fi nally,

indicate that the motor weakness suggests corticospinal

tract involvement.

Indicate that this constellation of defi cits is found in

Friedreich’s ataxia, an inherited progressive ataxia with

patholog y that fi rst appears in the dorsal roots.

Spinocerebellar tract involvement is an important dis-

tinguishing feature of this disorder.^18 – 21