Electromyography and nerve conduction velocities (NCVs) assess for abnormalities of the neuromuscular apparatus, including anterior horn cells, peripheral nerves, neuromuscular junctions, and muscles. Normal muscle is electrically silent at rest. Spontaneous discharge of motor fibers (fibrillations)or groups of muscle fibers (fasciculation) indicates denervation, revealing dysfunction of anterior horn cells or peripheral nerves. Abnormal muscle responses to repetitive nerve stimulation are seen with neuromuscular junction disorders, such as myasthenia gravis and botulism. The amplitude and duration of the muscle compound action potentials are decreased in primary diseases of muscle. NCVs assess the action potential transmission along peripheral nerves. NCVs are slowed in demyelinating neuropathies (Guillain-Barré syndrome). The amplitude of the signal is diminished in axonal neuropathies.
Imaging the brain and spinal cord is accomplished using CT or magnetic resonance imaging (MRI). CT is quick and accessible for emergency purposes. MRI provides fine detail and, with different sequences, permits detection of posterior fossa lesions, subtle cerebral abnormalities, vascular anomalies, low-grade tumors, and ischemic changes. For a child with a head injury or sudden headache, cranial CT is the study of choice because it can rapidly reveal intracranial hemorrhage or other large lesions. For a child with new-onset complex partial seizures, MRI is the study of choice, because an area of focal cortical dysplasia or other subtle lesions might not be apparent on CT. MRI also provides excellent views of the spinal cord. Cranial ultrasonography is a noninvasive bedside procedure used to visualize the brain and ventricles of infants and young children with open fontanelles.
Headache is a common symptom among children and adolescents. Headaches can be a primary problem (migraines, tension-type headaches) or secondary to another condition. Secondary headaches are most often associated with minor illnesses such as viral upper respiratory infections or sinusitis, but may be the first symptom of serious conditions (meningitis, brain tumors), so a systematic approach is necessary.
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The temporal pattern of the headache must be clarified. Each pattern (acute, recurrent-episodic, chronic-progressive, chronic-nonprogressive) has its own differential diagnosis (Table 180-1).
Tension-type headaches are the most common recurrent pattern of primary headaches in children and adolescents. They are generally mild and lack associated symptoms, so are not typically disruptive to patients’ lifestyle or activities. The pain is global and squeezing or pressing in character, but can last for hours or days. There is no associated nausea, vomiting, phonophobia, or photophobia. Headaches can be related to environmental stresses or symptomatic of underlying psychiatric illnesses, such as anxiety or depression.
Migraine headaches are another common type of recurrent headaches and frequently begin in childhood. Headaches are stereotyped attacks of frontal, bitemporal, or unilateral, moderate to severe, pounding or throbbing pain that are aggravated by activity and last 1 to 72 hours. Associated symptoms include nausea, vomiting, pallor, photophobia, phonophobia, and an intense desire to seek a quiet dark room for rest. Toddlers may be unable to verbalize the source of their discomfort and exhibit episodes of irritability, sleepiness, pallor, and vomiting. Migraines can be associated with auras that may be typical (visual, sensory, dysphagic) or atypical. Aura can precede or coincide with the headache and typically persists for 15 to 30 minutes. Visual auras consist of spots, flashes, or lines of light that flicker in one or both visual fields. Atypical auras may also consist of brief episodes of unilateral or perioral