RAMB - Julho 2016

urrent

clinical

approach

patients

with

disorders

consciousness

ssoc

ras

2016; 62(4):377-384

381

gate gaze to the stimulated side and a fast corrective move-

ment or nystagmus in the contralateral direction. Loss of

the fast phase is observed in comatose patients. This is a

good examination in cases of suspected psychogenic or-

igin of the coma. Obviously, a brainstem injury may lead

to absent response by interrupting this reflex.

Through these maneuvers we can observe the integ-

rity of oculomotor pathways in the brainstem and clear-

ly show the palsy of isolated cranial nerves. The absence

of a bilateral reflex response can indicate the presence of

extensive lesions in the brainstem.

Motor response

The motor examination of comatose patients is carried

out initially through observation of posture at rest, the

presence of spontaneous movement or response to ver-

bal or painful stimuli. The motor response should be an-

alyzed in comparison to the opposite side and after sym-

metrical stimulation, in the four limbs.

Head and eye deviation to one side and contralater-

al hemiplegia indicate supratentorial lesion, while devi-

ation to the same side of the hemiplegia may indicate a

brainstem lesion. External rotation of the lower limb may

be indicative of hemiplegia or hip dislocation.

Decerebrate posturing consists of bilateral extension

of the lower limbs and adduction and internal rotation

of the shoulders and extension of the elbows and wrists.

This generally means a bilateral mesencephalic and pons

lesion but can appear in severe metabolic encephalopa-

thies and supratentorial lesions involving the bilateral

corticospinal tract. Decorticate posturing consists of

bending the elbows and wrists, adduction of the shoul-

ders and extension of the lower limbs. Although not a

posture with a good topographic correlation, it usually

indicates injury above the brainstem. These abnormal

postures can be observed spontaneously or after painful

stimuli, and their presence might suggest a brainstem

herniation syndrome.

Other movements that can be observed are: tonic-

clonic seizures in epileptic seizures; myoclonus, observed

frequently in post-anoxic encephalopathy and other met-

abolic comas; reflex responses, such as the triple flexion

response of the lower limbs and the plantar reflex (Babin-

ski sign).

Respiratory pattern

In comatose patients, the respiratory pattern can help

us with the topographic diagnosis of the lesion. These

may include: Cheyne-Stokes respiration (bilateral hemi-

spheric lesions, severe heart failure), central neurogenic

hyperventilation (brainstem lesions), apneusis (lesions

in the dorsal-medial region of the lower half of the pons),

Biot’s respiration (lower pontine tegmental lesion) and

ataxic respiration (generally damage to the medulla ob-

longata).

aboratory

imaging

exams

The requested exams should include blood tests, electro-

lytes and biochemistry (sodium, calcium, phosphorus,

magnesium, chlorine, glucose), renal, hepatic and thyroid

functions, coagulogram, and blood gas. In selected cases,

quantify the serum level of certain drugs and toxicolog-

ical screening.

If there is suspicion of poisoning, aspiration and anal-

ysis of gastric contents can contribute to the diagnosis.

According to the availability of the service, the serum con-

centration of anticonvulsants, opioids, diazepinic agents,

barbiturates, alcohol and a large number of toxic sub-

stances can be measured.

White blood cell count can identify neutrophilic leu-

kocytosis, present in bacterial infections such as menin-

gitis, where it is usually greater than 12,000/mm

In some cases thyroid hormones and serum cortisol

may be requested, such as in suspected myxedema coma

and Addisonian crisis, respectively. One must mind that

water and sodium disorders such as hypo- or hypernatre-

mia can be results of brain disease that will directly or in-

directly affect the hypothalamic-pituitary axis.

Head tomography

This is essential upon suspicion of intracranial lesion and

must be the first image exam requested. It is performed

in a few seconds, is available in most emergency services

and has good sensitivity to detect bleeding (subarachnoid

hemorrhage, subdural hematoma, epidural hematoma,

or intraparenchymal hematoma), hydrocephalus, tumors

and extensive brain infarcts.

Sometimes it is difficult to determine if the abnor-

mality shown in the head CT scan is responsible for the

comatose state of the patient. In lesions that exert an

acute expansive effect, measuring the deviation from the

midline structures is an important parameter. Horizon-

tal deviations of 3 to 5 mm cause drowsiness; from 5 to

8 mm, they cause stupor; and greater than 9 mm, they

cause a coma. Patients with deviations exceeding 10 mm

and who are still in a coma, probably present lesions grow-

ing from weeks to months (e.g. chronic subdural hema-

toma, brain tumor). On suspicion of meningitis, carry

out head tomography whenever possible prior to per-

forming lumbar puncture, since herniation of the brain-