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  3. Clinical entry: Cone shells

Clinic: Cone shells

Examine for venom effects

Local Effects

  • Pain
  • Erythema
  • Swelling

Neurological effects

  • Descending flaccid paralysis (rarely progresses to involve bulbar and respiratory muscles):
    • Ptosis (not to be mixed up with tiredness / drowsiness; test: lid retraction with upward gaze).
    • Double vision (external ophthalmoplegia)
    • Difficulties to swallow (dysphagia) (bulbar paralysis) > inhalation of vomitus!
    • Difficulties to lift the head when lying on the back (‘broken neck syndrome’)
    • Cyanosis, shallow breathing, respiratory arrest (respiratory paralysis); respiratory arrest may be precipitated by obstruction of the upper airway by the paralysed tongue or inhaled vomitus. 
    • Weakness or loss of voluntary movement; movements of digits may still be possible, allowing the patient to communicate.
    • Loss of consciousness and generalized convulsions caused by hypoxaemia in patients who have respiratory paralysis.  

Species-specific envenoming pattern

The assessment of the envenoming pattern is based on the data from publication in which the identification of the cone shell is clearly specified and in accordance with accepted criteria.

  

Local effects

 Neurological effects 
Conus geographus    

Local effects

Sharp local pain at the time of the sting. Local swelling (Kohn 1963, McMichael 1971, Sutherland 1983).

Neurological effects

Rapid paralysis of the cranial nerves and skeletal musculature, including the respiratory musculature. Respiratory insufficiency and respiratory failure (Flecker 1936, Kohn 1963, McMichael 1971, Rice and Halstead 1968, Sutherland 1983). 

Case fatality rate

1/1 (Flecker 1936).
1/1 (Rice and Halstead 1968).

Clinical management

First Aid

Compression-immobilisation method (Sutherland 1983.

Seek medical assistance immediately.

Local treatment

Sting site

Pain control
Tetanus prophylaxis
Standard wound care
WHO (2010) 

Systemic supportive treatment

A general understanding of emergency medicine is required, or can be found in emergency medicine guidelines, e.g. ABCDE approach, WHO-ICRC Basic Emergency Care.

Follow ABCDE approach

WHO-ICRC Basic Emergency Care: approach to the acutely ill and injured

Obey Conus - specific features

see 'Species-specific envenoming pattern' above.

Key issues: 

Respiratory failure

Lifesaving in Conus envenoming:

Airway management
Breathing: Oxygen ⇨ assisted ventilation ⇨ mechanical ventilation

Endotracheal intubation and artificial respiration are the most important measures in the case of respiratory insufficiency.

Specific treatment (antivenoms)

No antivenom available.

References 

  • WHO-ICRC Basic Emergency Care: approach to the acutely ill and injured https://www.who.int/publications-detail-redirect/basic-emergency-care-approach-to-the-acutely-ill-and-injured  https://cdn.who.int/media/docs/default-source/integrated-health-services-(ihs)/csy/bec-quick-cards/becp-edu29-pdf-en-finl.pdf?sfvrsn=2532d61b_2 
  • WHO ABCDE Approach https://cdn.who.int/media/docs/default-source/integrated-health-services-(ihs)/csy/bec-quick-cards/becp-edu29-pdf-en-finl.pdf?sfvrsn=2532d61b_2
  • WHO (2010) Wound and lymphoedema management. WHO/HTM/NTD/GBUI/20101 I. 2010. https://www.who.int/publications/i/item/9789241599139 

Species-specific evidence

Conus sp.

  • Kohn (1963) 
    case reports.
  • McMichael (1971)
    case reports.

Conus geographus

Australia

  • Flecker (1936)
    1 patient; identification: morphological.

Guam

  • Rice and Halstead (1968)
    1 patient; identification: morphological.

Reviews

  • Kohn (1963)
  • McMichael (1971)
  • Sutherland (1983)