The sensory examination of newborns and infants is limited to observing the behavioral response to light touch or gentle sterile pinprick. Stimulation of the limb should produce a facial grimace. A spinal reflex alone may produce withdrawal movement of the limb. In a cooperative child, the senses of pain, touch, temperature, vibration, and joint position can be tested individually. The cortical areas of sensation must be intact to identify an object placed in the hand (stereognosis) or a number written in the hand (graphesthesia) or to distinguish between two sharp objects applied simultaneously and closely on the skin (two-point discrimination).
Analysis of cerebrospinal fluid (CSF) is essential when central nervous system (CNS) infection is suspected and provides important clues to other diagnoses (Table 179-2). Differentiating hemorrhagic CSF caused by a traumatic lumbar puncture (LP) from a true subarachnoid hemorrhage may be difficult. In most cases of traumatic LP, the fluid clears significantly as the sequence of tubes is collected. If there is clinical evidence of increased ICP (papilledema, depression of consciousness, focal neurologic deficits), caution must be exercised before performing an LP to limit risk of cerebral herniation. A computed tomography (CT) scan should be performed and confirmed to be normal before the LP if increased ICP is suspected. If increased ICP is present, it must be treated before an LP is performed.
Brain or parameningeal abscess Parasitic infection Leak of dermoid contents
Increased CSF protein Infection Guillain-Barré syndrome Inflammatory disease (ADEM, multiple sclerosis) Leukodystrophy Venous thrombosis Hypertension Spinal block (Froin syndrome) Carcinomatous meningitis
Bloody CSF Subarachnoid hemorrhage Subdural hemorrhage Intraparenchymal hemorrhage Hemorrhagic meningoencephalitis (group B streptococci, HSV) CNS trauma Vascular malformation Coagulopathy Traumatic lumbar puncture
ADEM, Acute disseminated encephalomyelitis; CNS, central nervous system;
HSV, herpes simplex virus. *In normal children, cells present should be lymphocytes.
The electroencephalogram (EEG) records electrical activity generated by the cerebral cortex. EEG rhythms mature throughout childhood. There are three key features present: background patterns, behavioral state modulation, and presence or absence of epileptiform patterns. The background varies with age, but there should be general symmetry and synchrony between the background of the two hemispheres without any localized area of higher amplitude or slower frequencies (focal slowing). Fixed slow wave foci (1 to 3 Hz) delta rhythms suggest an underlying structural abnormality (brain tumor, abscess, stroke). Bilateral disturbances of brain activity (increased ICP, metabolic encephalopathy) must be suspected when there is diffuse slow wave activity (delta frequency). Spikes, polyspikes, and spike-and-wave abnormalities, either in a localized region (focal) or distributed bihemispherically (generalized), indicate an underlying seizure tendency.