Conditions that Mimic Seizures

Introduction

• Some conditions share common features with epilepsy.
• They may be associated with altered levels of sensorium, abnormal movements, or cyanosis.
• Affected children may be inappropriately placed on many anticonvulsants with no response and some risk.
• Conditions that mimic epilepsy are refractory to antiepileptic drugs and the mode of treatment in them differs.

Benign Paroxysmal Vertigo (BPV)

• Seen in toddlers and is relatively rare beyond 3 years of age.
• The attacks develop suddenly and are associated with ataxia, causing the child to fall or refuse to walk or sit.
• Horizontal nystagmus may be evident during the duration of the attack.
• The child appears frightened and pale.
• Nausea and vomiting may be prominent.
• Consciousness and the ability to verbalize are not disturbed.
• The attacks vary in duration (seconds to minutes), frequency (daily to monthly), and intensity.
• A rotational sensation (vertigo) is verbalized by older children with BPV.
• These children are susceptible to motion sickness and may develop migraine headaches several years later, suggesting a relationship between BPV and migraine.
• Neurologic evaluation is often negative except for the finding of abnormal vestibular function detected by ice water caloric testing.
• Patients with clusters of attacks usually respond to diphenhydramine, 5 mg/kg/24 hr with a maximum of 300 mg/24 hr PO, IM, IV, or per rectum.

Night Terrors

• Common, especially in boys between 5 and 7 years of age.
• A night terror has a sudden onset, usually between midnight and 2:00 am during stage 3 or 4 of slow-wave sleep.
• The child screams and appears frightened, with dilated pupils, tachycardia, and hyperventilation.
• There is little or no verbalization; the child may thrash violently, cannot be consoled, and is unaware of parents or surroundings.
• Sleep follows in a few minutes, and there is total amnesia the following morning.
• Approximately one third of children with night terrors experience somnambulism.
• A short course of diazepam or imipramine may be considered for treatment of protracted night terrors while the family dynamics are under investigation.

Breath-Holding Spell

• This is a frightening experience for parents because the infant becomes lifeless and unresponsive owing to cerebral anoxia at the height of the attack.
• There are two major types of breath-holding spells: the more common cyanotic form and the pallid form.
• Rare before 6 months of age, they peak at about 2 years of age, and they abate by 5 years of age.

Cyanotic Breath-Holding Spell

• Often provoked by upsetting or scolding an infant.
• The episode is heralded by a brief, shrill cry followed by forced expiration and apnea.
• There is rapid onset of generalized cyanosis and a loss of consciousness that may be associated with repeated generalized clonic jerks, opisthotonos, and bradycardia.
• Results of an interictal electroencephalogram (EEG) are normal.
• A breath-holding spell can occur repeatedly within a few hours or recur sporadically, but it is always stereotyped.
• The management of breath-holding spells concentrates on the support and reassurance of the parents.

Pallid Breath-Holding Spells

• Less common than cyanotic breath-holding spells, but they share several characteristics.
• They are typically initiated by a painful experience, such as falling and striking the head or a sudden startle.
• The child stops breathing, rapidly loses consciousness, becomes pale and hypotonic, and may have a tonic seizure.
• Bradycardia with periods of asystole of longer than 2 seconds may be recorded.
• The interictal EEG is normal.
• Pallid spells can in some cases be induced spontaneously in the laboratory by ocular compression that produces the oculocardiac reflex, afferent stimulation of the trigeminal nerve, and efferent inhibition of the heart by way of the vagus nerve.
• Oral atropine sulfate may be of use.

Simple Syncope

• Results from decreased cerebral blood flow, usually secondary to systemic hypotension.
• Decreased blood flow causes loss of consciousness, and the concomitant ischemia influences the higher cortical centers to release their inhibiting influence on the reticular formation within the brainstem.
• Neuronal discharges from the reticular formation then produce brief tonic contractions of the muscles of the face, trunk, and extremities in approximately 50% of patients with syncope.
• During a syncopal episode, a child may have fixed upward deviation of the eyes that can be confused with convulsions.
• Simple syncope results from vasovagal stimulation and is precipitated by pain, fear, excitement, and extended periods of standing still, particularly in a warm environment.
• The EEG shows transient slowing during the attack but no seizure discharges. Simple syncope is uncommon before age 10-12 years but is quite prevalent in adolescent girls.
• Tilt-table testing is an effective method of producing symptoms in the majority of children with unexplained syncope.

Cough Syncope

• Most common in asthmatic children.
• It often occurs shortly after the onset of sleep, and the coughing paroxysm abruptly awakens the child.
• The patient's face becomes plethoric, and the child perspires, becomes agitated, and is frightened.
• Loss of consciousness is associated with generalized muscle flaccidity, vertical upward gaze, and clonic muscle contractions lasting for several seconds.
• Urinary incontinence is frequent.
• Recovery begins within seconds, and consciousness is usually restored a few minutes later.
• The child has no recollection of the attack except for the events surrounding the paroxysm of coughing.
• Coughing produces a marked increase in intrapleural pressure followed by a lowered venous return to the right side of the heart and an associated decrease in right ventricular output.
• Reduction of left ventricular filling follows, and a rapidly diminished cardiac output results in altered cerebral blood flow, cerebral hypoxia, and a loss of consciousness.
• The cornerstone of management for asthmatic children with cough syncope is an aggressive approach to the prevention of bronchoconstriction.

Prolonged QT Syndrome

• This is characterized by sudden loss of consciousness during exercise or an emotional and stressful experience.
• Loss of consciousness in association with exercise or stress is rarely due to epilepsy, and in every case a cardiac cause must be considered.
• The onset of the condition is typically in late childhood or adolescence, although onset in infancy may mimic sudden infant death syndrome.
• During the period of syncope, various cardiac arrhythmias are evident, particularly ventricular fibrillation.
• The child may recover within minutes or die during the event.
• Electrocardiography may show prolongation of the QT interval due to abnormal lengthening of the QT interval, especially during carefully monitored exercise.

Paroxysmal Kinesigenic Choreoathetosis

• This disorder is characterized by a sudden onset of unilateral or occasionally bilateral choreoathetosis or dystonic posturing of a leg or an arm and associated facial grimacing and dysarthria.
• The condition is precipitated by sudden movement, particularly on arising from a sitting position, or by excitement and stress.
• The attacks rarely persist for longer than a minute and are never associated with loss of consciousness.
• The age of onset is typically between 8 and 14 years, but the condition may begin as early as 2 years.
• The child may have several attacks daily, or they may be intermittent, occurring once or twice a month.
• Results of neurologic examination, EEG, and neuroimaging studies are normal, and neuropathologic studies in a few cases showed no abnormalities.
• Most reported cases are familial, suggestive of autosomal recessive inheritance.
• The attacks can be prevented by the use of anticonvulsants, especially phenytoin.

Shuddering Attacks

• Onset: 4-6 months of age and may persist to 6-7 years of age.
• They produce a peculiar posture, with sudden flexion of the head and trunk and shuddering or shivering movements similar to what must occur if ice-cold water is poured down the back of an unsuspecting individual.
• Attacks may be over 100 times per day followed by several symptom-free weeks.

Benign Paroxysmal Torticollis of Infancy

• Recurrent attacks of head tilt associated with pallor, agitation, and vomiting with an onset between 2 and 8 months of age.
• Child resists passive head movement.
• There is no loss of consciousness, and spontaneous remission occurs by 2-3 years of age.
• Abnormalities in vestibular function have been documented in them also.
• Some infants with benign paroxysmal torticollis develop migraine headaches later in childhood.

Hereditary Chin Trembling

• Hereditary chin trembling may be confused with epilepsy due to repeated episodes of rapid 3/sec chin trembling movements.
• These brief attacks are precipitated by stress, anger, and frustration and are inherited as an autosomal dominant trait.
• Findings on the neurologic examination and EEG are normal.

Narcolepsy

• Narcolepsy is a disorder that rarely begins before adolescence and is characterized by paroxysmal attacks of irrepressible daytime sleep, which is sometimes associated with transient loss of muscle tone.
• An EEG shows that the recurrent sleep attacks consist of rapid eye movement (REM) sleep.
• Patients with narcolepsy are easily aroused and become spontaneously alert.
• Modafinil acetamide, 200 mg/day PO, is superior to the stimulant drugs in the management of narcolepsy and has fewer adverse side effects.

Cataplexy

• Here, a child experiences sudden loss of muscle tone and falls to the floor because of laughter, stress, or frightening experiences.
• No loss of consciousness, but they lie without moving for a few minutes until normal body tone returns.
• Treatment consists of scheduled naps, amphetamines, methylphenidate, tricyclic antidepressants, and counseling.
• The stimulant and antidepressant drugs commonly produce side effects including anxiety, euphoria, hypersomnolence, and the development of tolerance.

Rage Attacks or Episodic Dyscontrol Syndrome

• This can be confused with complex partial seizures.
• Patients develop sudden and recurrent attacks of violent physical behavior with minimal provocation.
• The attacks consist of kicking, scratching, biting, and shouting (including abusive and profane language).
• An affected child or adolescent cannot seem to control the behavior and may seem momentarily psychotic throughout the attack.
• The episode is followed by fatigue, amnesia, and sincere remorse.
• A routine EEG may show nonspecific abnormalities in patients with the rage syndrome.
• The EEG in such patients during the attack remains normal.

Masturbation or Self-Stimulation

• Children with this condition have repetitive stereotyped episodes of tonic posturing associated with copulatory movements, but without manual stimulation of the genitalia.
• The child suddenly becomes flushed and perspires, may grunt and breathe irregularly, but has no loss of consciousness.
• The masturbatory activity has a sudden onset, usually persists for a few minutes (rarely hours), and tends to occur during periods of stress or boredom.
• The examination should include a search for evidence of sexual abuse or abnormalities of the perineum, but in most cases a cause is not found.
• Treatment consists of reassurance that the self-stimulatory activity will subside by 3 years of age and that no specific therapy is required.

Pseudoseizures

• Occur typically between 10 and 18 years of age and are more frequent among girls.
• Pseudoseizures occur in many patients with a past history of epilepsy and in some with ongoing true seizures.
• A pseudoseizure may be quite realistic but frequently is bizarre, with unusual postures, verbalizations, and uncharacteristic tonic or clonic movements.
• There are several distinguishing features of a pseudoseizure, including:
  • Lack of cyanosis
  • Normal reaction of the pupil to light
  • No loss of sphincter control
  • Normal plantar responses
  • Absence of tongue biting or injury during the attack
• Many patients moan or cry during a pseudoseizure, and some patients can be persuaded to have an attack on request by the physician.
• Patients with pseudoseizures are likely to have a neurotic personality.
• It is not unusual to find a patient taking three or four anticonvulsants, which, of course, have no effect.
• The most reliable method of differentiating epilepsy from suspected pseudoseizures is to record an attack.
• The EEG shows an excess of muscle artifact during the pseudoseizure but a normal background rhythm devoid of seizure discharges.
• After a true epileptic seizure, there is a significant increase in serum prolactin, whereas there is no change from the baseline at the termination of a pseudoseizure.

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