Approach to Common Emergencies in Pediatric Neurology

(Video 38.1). The onset of symptoms may be acute or subacute. The most common age of onset is 2 years. Prompt diagnosis of OMS is important because there is a strong association between OMS and neuroblastoma (NB). The reported percentage of patients with children with OMS and NB varies widely in the literature from 2% to 3% to 100%. Approximately 2% to 3% of children with an NB develop OMS. The minority of patients will recover completely with treatment. However, the majority of patients have lasting motor and cognitive disabilities despite aggressive immunomodulatory treatment.

2. Evaluation. The diagnosis is made clinically. A proposed international definition for OMS requires a patient to have at least three of the following: (1) myoclonus and/or ataxia; (2) opsoclonus or ocular flutter; (3) behavioral and/or sleep disturbance; and (4) NB. However, once the diagnosis of OMS is made, the patient needs a thorough evaluation for an occult NB including MRI or CT scan of the chest, abdomen, and pelvis and measurement of urine catecholamines. If these studies are not fruitful, then a radiolabeled iodine scintigraphy scan should be considered.

3. Treatment. Oncology should be consulted for management if the patient is found to have an NB and some patients may improve with treatment of the NB alone. However, many patients require immunomodulatory treatment. The literature does not support one specific regimen. Patients can be treated with steroids (e.g., prednisone or prednisolone, dexamethasone, or adrenocorticotropic hormone). Alternatively, steroid-sparing regimens with IVIG, azathioprine, rituximab, or cyclophosphamide are options.

B. Baclofen withdrawal.

1. Introduction. Baclofen is used frequently to treat spasticity, either orally or via an intrathecal pump. Intrathecal delivery of the drug is much more potent. Unfortunately, mechanical problems with the pump or failure to refill the reservoir may disrupt intrathecal administration of the drug. Abrupt withdrawal of baclofen can be fatal and is characterized by increased spasticity, hyperthermia, agitation, or loss of consciousness. Eventually, patients develop rhabdomyolysis, seizures, metabolic acidosis, hypotension, arrhythmias, and ultimately death.

2. Evaluation. The signs and symptoms of baclofen withdrawal mimic septic shock, which is a much more common diagnosis; thus, the first step toward effective treatment is consideration of the diagnosis. The baclofen pump should be interrogated to look for any anomalies in drug delivery and to ensure that the reservoir is not dry. Plain films should be done to look for fractures or displacement of the catheter. If these first two steps are not helpful and baclofen withdrawal is suspected, then a dye study can be done to further investigate the catheter. Serial CK levels need to be followed given the risk of rhabdomyolysis. For severe cases, chemistries/renal function and urine output must be followed and patients require close temperature and cardiovascular monitoring.

3. Treatment. As soon as a diagnosis is made, the problem with drug delivery should be corrected urgently. In the interim, fevers should be aggressively managed with antipyretics and external cooling devices. Insensible fluid losses are high so patients may need aggressive fluid resuscitation, especially if CK is elevated. If intrathecal drug delivery cannot be reestablished quickly, then high-dose systemic baclofen, diazepam, or other benzodiazepines such as a midazoalam drip may blunt the withdrawal. Much higher doses of enteral baclofen is needed to achieve the same effect and also will have more systemic side effects. Case reports also suggest that dantrolene might be an effective treatment.

C. Status dystonicus.

1. Introduction. Status dystonicus is an uncommon movement disorder emergency but it can lead to significant morbidity and mortality if it is not quickly recognized and treated. As the name implies, status dystonicus is development of severe and unrelenting dystonia. Similar to baclofen withdrawal, which is discussed above, patients can develop severe hyperthermia, dehydration, and rhabdomyolysis with resulting metabolic acidosis, acute renal failure, and electrolyte derangements, especially life-threatening hyperkalemia. Dystonia of the respiratory muscles can lead to respiratory failure. Status dystonicus may occur secondary to an exacerbation of a patient’s baseline dystonia triggered by pain, stress, or infection. Certain medications, such as dopamine antagonists, also may trigger an attack. Patients with aristaless homeobox (ARX) gene mutations seem to be particularly prone to developing recurrent episodes of status dystonicus.

2. Evaluation. Diagnosis is made clinically. Mimickers such as malignant hyperthermia, baclofen withdrawal, or neuroleptic malignant syndrome should be considered, although therapy is similar for many of these diagnoses. Temperature and vital signs must be carefully monitored. Blood gas, chemistries (including renal function), and CK should be carefully followed. Because of the risk of acute renal failure, urine output also should be monitored carefully.

3. Treatment. If the patient is having increasing dystonia but is not yet in status, then analgesic and sedation medications should be trialed. Chloral hydrate may help the patient sleep and break the cycle of dystonia. Benzodiazepines also have been reported to be efficacious. Clonidine, which is an alpha agonist, is an option for treatment, particularly if the patient has significant hypertension and tachycardia. If a trigger can be identified, such as a source of pain, then it should be eliminated. If severe hyperthermia, metabolic derangements, or rhabdomyolysis already have begun, then patients must be treated quickly and aggressively and should be monitored in a critical care setting. Patients with dystonia of the neck or respiratory muscle may require intubation because of upper airway obstruction. Aggressive rehydration, antipyretics, and mechanical cooling should be initiated. If frequent intermittent doses of sedation/pain medication are not effective, then continuous infusions of medication, such as midazolam or dexmedtomidine, should be initiated and elective intubation may be required. Propofol has been used in adults but prolonged infusions should not be used in children because of the increased risk of propofol infusion syndrome. If continuous sedative medications fail to control the life-threatening symptoms, then the next step is paralysis. Once temporizing measures are in place, long-term dystonia-specific interventions can be started that will help reverse the process. Trihexyphenidyl, baclofen, gabapentin, and tetrabenazine are some pharmacologic options. Ultimately for severe, refractory cases, invasive interventions such as intrathecal baclofen pump placement, deep brain stimulation, and/or pallidotomy may be necessary.

EPILEPSY

There are several types of epilepsy that require urgent recognition, such as infantile spasms, in children. These are described in detail elsewhere in this book. We would refer the reader to Chapter 42.

A. RSE or super-refractory status epilepticus.

1. Introduction. RSE describes ongoing seizure activity despite administration of two or three appropriate drugs. As the seizure continues, it becomes less responsive to drugs, likely due to internalization of gamma amino-butyric acid receptors and upregulation of NMDA receptors. Prolonged seizures eventually result in cerebral injury and potentially cerebral edema. Unchecked status epilepticus also has direct detrimental effects on multiple organ systems including the cardiac and respiratory systems. Recent data suggest that a higher seizure burden in critically ill children is associated with worse outcomes even after controlling for severity of illness. Thus, RSE is a true neurologic emergency.

2. Evaluation. For a child with no prior history of seizures, one must ensure that reversible causes of seizures, such as hyponatremia, hypoglycemia, or hypocalcemia, are ruled out or effectively treated. After reversible causes of status epilepticus are eliminated, the evaluation for an underlying cause for new-onset seizure/status epilepticus is guided by individual patient characteristics. Continuous EEG monitoring is important for ongoing management of RSE. Over time, clinical monitoring for seizures becomes less reliable because patients develop electroclinical dissociation. Adult studies have shown that there is a high incidence of nonconvulsive seizures after convulsive status epilepticus; smaller studies suggest that this phenomenon also occurs in children.

3. Treatment. The goal of treatment can be either cessation of electrical evidence of seizures or achieving suppression burst pattern on EEG. RSE treatment requires timely administration of antiepileptics and rapid escalation to continuous infusions of medication. Most patients need blood pressure and respiratory support as medications are titrated upwards so these children should be monitored in a critical care setting. Multiple different treatment pathways exist. Second-line medications after benzodiazepines include fosphenytoin or phenytoin, valproic acid, levetiracetam, phenobarbital, and lacosamide. Third-line medications are generally continuous infusions such as midazolam, pentobarbital, ketamine, or inhaled anesthetics. A trial of pyridoxine should be considered in neonates. Hypothermia is being studied as a possible therapy for super-refractory status epilepticus but is not a well-established treatment. A proposed algorithm for management of adult generalized status epilepticus can be found in Chapter 63. Of note, though, propofol is frequently used in adults but should not be routinely used in children because of the increased risk of propofol infusion syndrome. Once seizure control or suppression burst is achieved, general practice is to allow 24 to 48 hours of “brain rest” before attempting to wean the continuous infusions.

Key Points

• Although the manifestations and etiology of cerebrovascular dysfunction in children differ from those of adults, vascular lesions are far more common among children than once suspected. Prompt diagnosis and treatment of these children can minimize the likelihood of recurrent stroke and promote functional recovery.

• Immune-mediated encephalopathies often lead to devastating, sometimes permanent, neurologic dysfunction. In contrast to adults with these conditions, underlying malignancy is relatively uncommon among children with immune-mediated encephalopathy. Immunomodulation with IVIG, burst of high-dose steroids, PLEX, or other therapies is often effective.

• Therapeutic hypothermia minimizes the severity of permanent neurologic impairment in neonates with hypoxia and ischemia, but there is no evidence that hypothermia offers the same benefit in older children.

• It is important to recognize opsoclonus in children, because it often constitutes a paraneoplastic syndrome. The most common underlying tumor in children with opsoclonus is NB, and recognition of the opsoclonus in these individuals often initiates a systematic search for the tumor and earlier removal. In some instances, opsoclonus may improve following tumor removal, while other children require immune modulation therapy in addition.

• Children with acute or rapidly progressive neuromuscular weakness from whatever cause are at high risk for respiratory failure and may need to be intubated because of respiratory muscle weakness and/or loss of an effective cough and gag. It is preferable to anticipate this problem and electively intubate rather than awaiting the occurrence of frank respiratory failure.

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