By Po-Chang Hsu and Hector Caraballo
Infantile hypotonia presents significant challenges in the pre-hospital setting. As a paramedic or EMT you will likely respond to calls involving both acutely and chronically ill children. The skill of accurately and rapidly assessing a pediatric patient’s tone is essential in the first moments of an encounter. Developing an approach to handling severe abnormalities comes with training and experience. In general, preparing for these encounters both in thought and in practice is a must to do your best out there. This article will explore hypotonia and provide background on the topic, as well as a few cases, that may aide pre-hospital professionals in further improving their preparedness in this arena.
The word hypotonia should not be confused with weakness. Hypotonia means low muscle tone, while weakness means low muscle strength. In the acute setting hypotonia tends to be a diffuse finding, whereas weakness tends to be a localized finding. Early signs of infantile hypotonia include poor motor control, weak cry and suck, and, chronically, delayed motor skill development. Severe manifestations of hypotonia may exhibit as paralysis, as in botulinum toxin exposure, leading to feeding difficulty and respiratory failure.
Hypotonia can be classified as acquired or congenital. Acquired hypotonia usually has more acute causes including infections, traumas, metabolic disorders, and heart diseases, many of which can be lethal if left untreated. The causes can also be congenital, involving diseases such as Down syndrome. Infantile hypotonia due to congenital causes are more benign in nature overall, but can be key factors in an infant’s physiologic reserve in the setting of even minor acute illnesses. The following four (4) cases illustrate different causes of infantile hypotonia you may encounter.
Case 1: Baby Sarah
A mother calls the ambulance because her 6-month-old baby Sarah is having difficulty waking up from sleep this afternoon. You hear that Sarah has been having a fever and some simple questions reveal that she has had decreased oral intake and decreased number of wet diapers for the past few days. Baby Sarah exhibits signs of low muscle tone, including frog-leg posture. Her breathing is slightly fast and shallow without signs of overt respiratory distress. When you check Sarah’s capillary refill, it is more than 4 seconds. Sarah also has mottled skin appearance with dry lips and mouth. You proceed to place an IV and notice that Sarah does not respond very vigorously to the needle pricks. Instead, her whimper is barely audible. You begin fluid resuscitation and assess Sarah’s vital signs as you transport her to the hospital.
Infections should be suspected in babies who have both hypotonia and fever at the same time. The most common types of infections that can lead to hypotonia include meningitis and encephalitis, but the differential is very broad. First responder’s role in a case of hypotonic baby is to focus on the ABC’s (Airway, Breathing, and Circulation), but perhaps not in that exact order. Each call is unique, but in this case supporting circulation with fluid resuscitation and supporting breathing with oxygen in an infant who is otherwise breathing spontaneously and able to ventilate render airway management less of a priority. Obtaining a finger stick glucose will also yield valuable information. When possible, history can be an important part of narrowing the underlying causes, but the main goal is supportive care while transporting to a clinical environment with more resources.
Case 2: Baby Sam
You arrive at the home where a 9-month-old baby Sam was found unresponsive. The mother claims she forgot to put Sam back into the crib after changing his diaper on the changing table. You pick up Sam from the bed to the stretcher. While doing so, you observe that Sam is floppy. He also has episodes of hypertonic extension of the arms and legs lasting seconds when you lay him on the stretcher. Sam lies motionless as an IV is placed and moans. You assess his Glasgow Coma Scale is 4 (E1V2M1). An airway is secured. Secondary survey shows bruises on the head and arms of the patient. Further examination reveals that Sam’s pupils are unequal in size.
An initial assessment includes determining a Pediatric Glasgow Coma Scale score. The initial stabilization includes supportive measures to ensure the ABC’s of the patient. Cervical spine immobilization, if spinal trauma is suspected. A secondary survey should then be performed to evaluate whether other injuries are present. This patient’s bruising pattern raises the suspicion of child abuse. His unequal pupil sizes indicate intracranial hemorrhage, which can be a result of non-accidental trauma. It is likely baby Sam will require emergent neurosurgical interventions followed by pediatric intensive care (PICU) level attention. Rapid transport to the hospital for further management or air transport to the nearest appropriate facility while supporting a patient like baby Sam places the pre-hospital professional in a vital link in the chain of recovery this event.
Case 3: Baby Jim
You are the first responder on the scene. The parents called 911 when they saw their 3-day-old baby Jim was having seizure-like activity. Jim is not actively seizing when you arrive. His legs are spread out like a frog in the crib. Jim seems lethargic and is breathing rapidly when you examine him. When you pick up Jim, his four extremities hang loosely from the body. Assisted ventilation is provided. You ask the parents for more history and find out that Jim has not been able to latch on his mother’s breast or tolerate formula feeding since birth. No history of trauma or illness is found. No other complications related to his full-term birth. Rapid finger-stick glucose reveals a blood glucose of 20mg/dL. You administer Glucagon intramuscularly, then proceed to establish an IV for administration of D10.
Infantile hypotonia can be caused by metabolic disorders, which include genetic diseases, electrolyte imbalances, and hypoglycemia. Infant hypoglycemia can manifest as tremors, tachypnea, altered state of consciousness, seizures, and hypotonia. Rapid finger-stick glucose and treatment of hypoglycemia at the scene and en-route is a necessary time sensitive intervention. Treatment for symptomatic hypoglycemic infant involves administration of IV fluid with dextrose.
Case 4: Baby Tim
A nervous mother called the ambulance when her 8-month-old baby Tim stopped breathing and skin turned blue during his sleep. The mother reports the episode lasted about 20 seconds and Tim started breathing again. The first responders examine Tim in his crib, who is now awake. The responders find that Tim has low muscle tone when lying on the bed. However, Tim is well otherwise with no trouble breathing, normal skin appearance, and at a baseline mental status according to his mother. The mother says that Tim has trouble sitting up and cannot roll over, unlike his older brother could do at the same age. Further questioning reveals Tim was diagnosed with Down syndrome as a newborn.
Chromosomal disorders, such as Down syndrome, are a common cause of congenital hypotonia in infants. Certain congenital spinal and muscular diseases can also exhibit as hypotonia. But the astute clinician is careful not to attribute the above episode to a chronic condition. The presentation above is concerning for a cyanotic event less than one minute in a child under a year old, who has returned to baseline. In the past these events were called Acute Life-Threatening Events (ALTE), but new nomenclature is a lot less ominous: Brief Resolved Unexplained Event (BRUE). Re-assurance to the parents, supportive care if needed and transport to the nearest appropriate facility for further evaluation is recommended.
The job of first responders in infantile hypotonia is to identify, assess and support patients in the acute cases and stabilization in route to definitive care settings. Signs of hypotonia, including lack of muscle tones, a frog-leg posture, and decrease motor functions. History from parents may help to narrow the differential diagnosis. Above all else preparing for these types of cases before they are encountered permits a higher likelihood of peak performance in response to these very stressful types of cases.
Practicing scenarios in a simulated setting to get familiar with identifying causes and practicing management are integral to preparedness. While it may be more difficult for traditional baby mannequin to simulate physical findings of hypotonia, new technologies using virtual patients can mimicthe physical signs that a hypotonic baby would exhibit. This helps first responders’ training in identifying early signs of infantile hypotonia and in providing better management. Simulation also allowserrors to be made in a safe environment for both patient and health care professional, such as EMTs, paramedics and other first responders.
Dr. Hsu graduated with a biology masters from Harvard University and received a MD degree from Tufts Medical School. He has interests in emergency medicine, pediatrics, and neonatology.
Hector Caraballo, MD, FAAEM is a practicing Board Certified Emergency Physician and Chief Medical Officer at MedCognition.
MedCognition has developed a mixed reality system that is a great training tool allowing for enhanced high fidelity training for those tasked with caring for acutely ill infants. Click here to read more.