Botulism

Rare, life‑threatening neuroparalytic syndrome caused by botulinum neurotoxin (usually from *Clostridium botulinum*); toxin blocks acetylcholine release at neuromuscular junctions, leading to flaccid descending paralysis.

• Botulism can cause rapid respiratory failure and death if not recognized and treated immediately. It's a classic exam example of descending paralysis (vs ascending in Guillain‑Barré) and highlights the need for urgent antitoxin (often via public health authorities).

• Symmetric descending paralysis often starting with cranial nerve symptoms (diplopia, ptosis, dysphagia, dysarthria), then spreading downward to trunk and limbs. Notably, patients are usually afebrile, have no sensory loss, and remain mentally alert.
• Foodborne botulism: Adult after ingesting home‑canned or improperly preserved foods (low acid, anaerobic). Onset ~12–36 hours post-meal with possible GI upset (nausea, vomiting, abdominal pain) followed by the characteristic neurological symptoms.
• Infant botulism: Typically a 2–8 month-old with constipation as an early sign, then poor feeding, weak cry, floppy head and limbs ("floppy baby syndrome"). Often history of honey consumption or environmental dust exposure (ingested spores that germinate in the gut).
• Wound botulism: Seen in IV drug users (e.g., black tar heroin) or deep traumatic wounds. C. botulinum spores contaminate the wound and produce toxin in vivo. Presents ~1–2 weeks after injury with similar descending paralysis; look for an infected wound (and no GI prodrome).
• Iatrogenic botulism: Due to cosmetic or therapeutic botulinum toxin injections (e.g., for wrinkles, dystonia, migraines). Overdose or accidental spread of toxin can cause localized or generalized botulism symptoms (cranial nerve palsies, weakness).

1. Maintain a high index of suspicion: any patient with acute cranial nerve palsies and descending paralysis (especially if afebrile and sensory intact) should prompt consideration of botulism and immediate action.
2. Gather history for exposures: ask about home-canned foods, preserved fish, honey ingestion in infants, injection drug use or recent Botox injections.
3. Do not wait for labs—immediately notify public health authorities (state health department/CDC) and obtain botulism antitoxin if clinical suspicion is high. Early antitoxin can halt progression of paralysis.
4. Perform diagnostic testing in parallel: serum and stool toxin assays (mouse bioassay or ELISA), stool or wound culture for *C. botulinum*, and electrophysiology (EMG) studies. EMG classically shows an incremental increase in muscle response with high-frequency repetitive stimulation (presynaptic facilitation), supporting a presynaptic neuromuscular junction disorder.
5. Manage the airway and breathing: botulism often requires ICU care for respiratory monitoring. Frequent measurement of vital capacity can guide need for intubation and mechanical ventilation (many patients require ventilation for weeks until neuromuscular function recovers).
6. For wound botulism, also surgically debride the wound and give targeted antibiotics (after antitoxin) to eliminate the source. For infant botulism, avoid antibiotics (they can worsen toxin release on bacterial lysis) and use human botulism immune globulin (BabyBIG) as directed.

1. Antitoxin administration as soon as possible – equine heptavalent botulinum antitoxin (HBAT) for adults; human-derived BIG-IV for infants. Do not delay antitoxin while awaiting confirmation.
2. Supportive care in ICU: meticulous respiratory support (monitor vital capacity, early intubation if needed), cardiac monitoring, and rehab. Patients may need weeks of ventilatory support until neuromuscular junctions recover.
3. Wound botulism: after giving antitoxin, treat with IV penicillin G (or metronidazole) and surgical debridement of the wound to remove the source of toxin. (Infant botulism: no antibiotics; they are contraindicated as they may worsen toxin release.)
4. No role for antibiotics in foodborne botulism (since toxin is preformed); focus is on antitoxin and supportive measures. Consider gut decontamination (e.g., cathartics) if a known food ingestion was recent.

• Mnemonic: remember the 4 D's of botulism – Diplopia, Dysarthria, Dysphagia, Dyspnea (double vision, difficulty speaking, swallowing, breathing). These stem from early cranial nerve involvement.
• Never give honey to infants under 1 year (infant botulism risk). Even a small taste can contain C. botulinum spores → toxin production in the infant's gut.
• Home-canned foods with bulging lids (gas production) are a big red flag – they should be discarded to prevent botulism.

• Suspected botulism is a medical emergency – involve public health authorities and give antitoxin immediately. Never wait for lab results if clinical presentation fits botulism.
• Never feed honey to an infant <12 months old – even a small exposure can cause infant botulism (spores germinate in the infant's immature gut).
• Multiple patients with the same meal developing similar paralysis should raise alarm for a botulism outbreak – requires rapid public health intervention.

1. Acute cranial nerve palsies + descending paralysis (especially with risk factors like home-canned food, infant with honey, or wound infection) → Suspect botulism.
2. If botulism suspected: call state health department/CDC immediately for emergency antitoxin release; this should be done as soon as clinical diagnosis is considered.
3. Hospitalize in ICU. Monitor respiratory status closely (serial negative inspiratory force or vital capacity); be prepared for early intubation if any signs of respiratory muscle weakness.
4. Obtain diagnostic samples (serum, stool, vomitus, wound exudate) for toxin assay and culture, and consider EMG studies – but do not withhold treatment pending results.
5. Administer antitoxin as soon as available. For wound botulism, also perform wound debridement and start IV penicillin after antitoxin. For infant botulism, administer BIG-IV (BabyBIG) and provide supportive care (no antibiotics).

• Blurred vision, ptosis, and difficulty swallowing in an adult after eating home-canned food → foodborne botulism (descending paralysis from preformed toxin).
• A 3-month-old infant with constipation, poor feeding, and generalized hypotonia (floppy baby) after honey exposure → infant botulism.
• IV drug user with an infected wound who develops diplopia, dysphagia, and descending limb weakness → wound botulism.