History of Present Illness
The patient is a 22 year old female with no significant past medical history who presents to the ED with a chief complaint of dysphagia. The patient first noticed difficulty swallowing solid foods 2 weeks ago. She states that she felt like food was getting caught in her throat. Initially she only had difficulty swallowing solid foods and was able to eat soft foods and liquids. However, she reports that over the course of two weeks her condition gradually worsened to the point where she could no longer tolerate fluids. She states that she has pain in the back of her throat when she attempts to swallow.
She denies any fevers, chills, congestion, swollen lymph nodes or neck stiffness. She reports that she has been to 3 different emergency departments and urgent care centers in which she was treated empirically for strep throat. The patient states that she has felt more fatigued than usual. Upon inquiring about any possible sick contacts, her friend reports that the patient’s roommate is in the ICU for “some autoimmune disorder,” but did not know any specifics. She denies any past medical history, takes no medications, denies allergies, and denies any tobacco, alcohol, or illicit drug use.
Vitals: T: 98.3 F (36.8 C) HR: 95 RR: 16 BP: 115/70 O2: 99% on room air
HEENT: Normocephalic, Atraumatic. Patient had appreciable bilateral ptosis. Examination of the patient’s eyes revealed pupils that were equal and reactive to light. Her extra ocular muscles were intact, though she had limited lateral abduction of her eyes bilaterally. Examination of the oropharynx revealed large tonsils without exudate or erythema. The palate was symmetrical and uvula midline. She exhibited no trismus. No cervical lymphadenopathy was appreciated.
Pulmonary: Clear to auscultation bilaterally, no wheezes, rhonchi, rhales
Abdomen: Normal bowel sounds, soft, non-tender, non-distended. No rebound or guarding
Neuro: AAOx4, On CN exam she has bilateral lateral gaze palsy and diplopia, otherwise CN intact. Sensation to light touch was intact throughout. Strength was grossly symmetric in bilateral upper and lower extremities 5/5 strength. Gait was normal.
Emergency Department Course
Given the patient’s multiple visits for “sore throat” and her neurologic findings, there was heightened suspicion for a more serious process. Basic laboratory tests were ordered, including CBC, BMP, ESR, CRP. She had an elevated white count of 15.4, an elevated CRP of 23, and mild electrolyte disturbance with Na+ of 153 and K+ of 3.2.
Given concern for myethenia gravis ice pack test was performed which did not produce fatigue. A NIF and FVC were completed at bedside to assess the patient’s respiratory function, which revealed a NIF of -27 (normal <-25), and an FVC of 1.3 liters (normal 3-5L)
Bedside nasopharyngoscopy was performed to assess for any structural etiologies. This only revealed pooled secretions with otherwise a normal examination.
Given the patient’s dysphagia and neurologic findings neurology was consulted. They were also impressed with the patient’s neurologic findings and recommended admission to their service. At this time myasthenia gravis and guillan barre syndrome were the most significant differential diagnoses being considered. However, the neurology resident looked into the friend’s information about the patient’s roommate and discovered that she was a patient in the neuro ICU unit (NSICU) who was currently intubated for respiratory failure. Given the presentation of the patient and her roommate, the team did not feel this was a coincidence and botulism was elevated to the top of the differential. The patient was subsequently admitted to the NSICU for further management.
Overnight in the neuro ICU, the patient underwent elective intubation for slightly but progressively worsening NIF and FVC values. Further history from friends and family gathered by the inpatient team revealed that on the night prior to the onset of their symptoms both the patient and her roommate had shared a dinner consisting of chicken with home canned pesto sauce. The patient’s mom brought in the pesto sauce, and it was sent to the State Health Department for analysis which eventually revealed presence of botulinum toxin. The patient was administered botulism antitoxin attained from the CDC.
On her 4th day in the ICU, the patient showed improvement in her respiratory parameters and was successfully extubated. She continued to have some difficulty controlling secretions and thus tube feedings were continued. She was transferred days later to a rehabilitation center for continued speech therapy and management of her tube feeds.
Botulism is an acute illness causing paralysis that is mediated by a neurotoxin produced by Clostridium botulinum. C. botulinum is a sporulating, anaerobic, gram-positive bacillus found in many soil and aquatic sediments. The toxin, botulinum neurotoxin (BoNT), can be of several types, differentiated by varying antigenicity, but types A, B, E and rarely F are most often associated with human disease.
BoNT, is an extremely potent neurotoxin that attacks the presynaptic terminal at the neuromuscular junction. It is estimated that as little as 1 g of aerosolized BoNT could cause the death of ~ 1.5 million people (McNally 1994). The neurotoxin, once absorbed into the body, acts as an active protease in the presynaptic terminal that prevents the release of neurotransmitters (namely acetylcholine etc.) into the synaptic cleft and thus prevents signal transmission.
The four major forms of Botulism in humans are: infant, food-borne, wound, and adult intestinal toxemia botulism. In addition, there are very rare reports of disease caused by either inhalation or iatrogenic therapeutic injection of the toxin. Across the United States it is estimated that annually there may be as many as 250 cases of infant Botulism (Cox 2002), versus roughly 24 cases of food-borne disease (McLauchlin 2006) whereas only a few cases of adult intestinal toxemia have been reported (Shapiro 1998).
The rapidity of progression of the clinical course is determined by whether preformed toxin or spores that germinate in the intestinal tract are ingested. However the clinical presentation remains consistent as the toxin attacks cranial nerves producing symptoms including blurred vision, diplopia, ptosis, dysarthria, dysphonia and dysphagia (Demebek 2007). There are varying degrees of descending muscle paralysis beginning with the neck and progressing to include respiratory muscles often requiring mechanical ventilation.(CDC 2006) Death from botulism occurs secondary to respiratory arrest due to respiratory muscle paralysis/weakness and ultimate diaphragmatic failure. (Sobel 2005)
Left unrecognized or untreated, mortality from botulism may be as high as 40%. (Dembek 2007) However with treatment foodborne botulism has an overall mortality of 5-10%, wound botulism 15-17% and infant botulism less than 1%. Diagnosis is based on clinical presentation and history, and toxin identification from serum, stool, gastric aspirate, or vomitus or from growth of C. botulinum in culture. Treatment for botulism includes admission and aggressive supportive care. Spirometry, pulse oximetry, vital capacity should be followed sequentially as respiratory collapse can occur rapidly. Mechanical ventilation should be undertaken when vital capacity or negative inspiratory force is less than 30% of predicted. Medication treatment includes either an equine-derived antitoxin or a newly FDA approved (2013) human derived immune globulin against all 7 known serotypes of the nerve toxin. The human derived antitoxin has far less reported incidence of anaphylaxis as compared to the equine version. (Chan-Track 2013)
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Thanks to Nicholas Ludmer (PGY-1) and Phil Moschella (PGY-4), both of whom contributed to the content of this case study.