Plum and posner’s diagnosis of stupor and coma fourth Edition series editor sid Gilman, md, frcp

comes flaccid, tendon reflexes may be difficult

to obtain, and lower extremity posturing may

become flexor.

The medullary stage is terminal. Breathing

becomes irregular and slows, often assuming a

gasping quality. As breathing fails, sympathetic

reflexes may cause adrenalin release, and the

pupils may transiently dilate. However, as ce-

rebral hypoxic and baroreceptor reflexes also

become impaired, autonomic reflexes fail and

blood pressure drops to levels seen after high

spinal transection (systolic pressures of 60 to

70 mm Hg).

At this point, intervening with artificial venti-

lation and pressor drugs may keep the body alive,

and all too often this is the reflexive response in a

busy intensive care unit. It is important to rec-

ognize, however, that once herniation progresses

to respiratory compromise, there is no chance

of useful recovery. Therefore, it is important to

discuss the situation with the family of the pa-

tient before the onset of the medullary stage,

Cheyne-Stokes

Small range of contraction

DOLL’S HEAD MANEUVER

ICE WATER CALORICS

Small pupils

Same as Fig. 3–11 but easier

to obtain (absent nystagmus)

Legs stiffen and arms

rigidly flex

(decorticate rigidity)

Motionless

Respiratory

pattern

a.

Pupillary

size and

reactions

b.

Oculocephalic

and

oculovestibular

responses

c.

Motor

responses

at rest

and to

stimulation

d.

Same as Fig 3–11, but easier

to obtain (absent nystagmus)

Figure 3–12. Signs of central transtentorial herniation, or lateral displacement of the diencephalon, late diencephalic stage.

Structural Causes of Stupor and Coma

109

---

and to make it clear that mechanical ventilation

in this situation merely prolongs the process of

dying.

Clinical Findings in Dorsal

Midbrain Syndrome

The midbrain may be forced downward through

the tentorial opening by a mass lesion impinging

upon it from the dorsal surface (Figure 3–15).

The most common causes are masses in the

pineal gland (pinealocytoma or germ cell line

tumors) or in the posterior thalamus (tumor or

hemorrhage into the pulvinar, which normally

overhangs the quadrigeminal plate at the pos-

terior opening of the tentorial notch). Pressure

from this direction produces the characteris-

tic dorsal midbrain syndrome. A similar pic-

ture may be seen during upward transtentorial

herniation, which kinks the midbrain (Figure

3–8).

Sustained regular

hyperventilation

Rarely, Cheyne-Stokes

Fixed

DOLL’S HEAD MANEUVER

or

ICE WATER CALORICS

Midposition often

irregular in shape

Impaired, may be

dysconjugate

Arms and legs

extend and pronate

(decerebrate rigidity)

particularly on side

opposite primary

lesion

Usually

motionless

Respiratory

pattern

a.

Pupillary

size and

reaction

b.

Oculocephalic

and

oculovestibular

responses

c.

Motor

responses

at rest

and to

stimulation

d.

Impaired, may be

dysconjugate

Figure 3–13. Signs of transtentorial herniation, midbrain-upper pons stage.

110

Plum and Posner’s Diagnosis of Stupor and Coma

---

Pressure on the olivary pretectal nucleus and

the posterior commissure produces slightly en-

larged (typically 4 to 6 mm in diameter) pupils

that are fixed to light.

2

There is limitation of

vertical eye movements, typically manifested

first by limited upgaze. In severe cases, the eyes

may be fixed in a forced, downward position.

If the patient is awake, there may also be a

deficit of convergent eye movements and as-

sociated pupilloconstriction. The presence of

retractory nystagmus, in which all of the eye

muscles contract simultaneously to pull the

globe back into the orbit, is characteristic. Re-

traction of the eyelids may produce a staring

appearance.

Deficits of arousal are present in only about

15% of patients with pineal region tumors, but

these are due to early central herniation.

63,64

If the cerebral aqueduct is compressed suffi-

ciently to cause acute hydrocephalus, however,

an acute increase in supratentorial pressure may

ensue. This may cause an acute increase in

Eupneic, although often more

shallow and rapid than normal

Slow and irregular in rate

and amplitude (ataxic)

Fixed

DOLL’S HEAD MANEUVER

or

or

ICE WATER CALORIC

Midposition

No response

No response

No response to

noxious orbital

stimulus; bilateral

Babinski signs or

occasional flexor

response in lower

extremities when

feet stroked

Motionless and

flaccid

Respiratory

pattern

a.

Pupillary

size and

reaction

b.

Oculocephalic

and

oculovestibular

responses

c.

Motor

responses

at rest

and to

stimulation

d.

Figure 3–14. Signs of transtentorial herniation, lower pons-upper medulla stage.

Structural Causes of Stupor and Coma

111

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