Part of the title, “that was a curious incident,” is taken from Sherlock Holmes’ Silver Blaze. Here are two excerpts from the short mystery where the race horse was stolen at night from the stable and the dog had not barked.

“Is there any point to which you would wish to draw my attention?”

     “To the curious incident of the dog in the night-time.”

     “The dog did nothing in the night-time.”

     “That was the curious incident,” remarked Sherlock Holmes….

Later Holmes explains,

  “Before deciding that question I had grasped the significance of the silence of the dog, for one true inference invariably suggests others. The Simpson incident had shown me that a dog was kept in the stables, and yet, though some one had been in and had fetched out a horse, he had not barked enough to arouse the two lads in the loft. Obviously the midnight visitor was someone whom the dog knew well.”

 

Similarly it is difficult for the doctor  to appreciate what is not there: the absent reflex; the absence of tenderness at the site of the pain; the absent of breathe sounds and in the following case, “Just another Corneal abrasion,[i]” the cornea abrasion had not barked with pain.

“A 67-year-old woman came to the ophthalmic emergency department in August 2000, complaining of a sore, red, right eye. She had no history of trauma and no previous problems with her eyes. On examination, her visual acuity was 6/6 in the right eye, and 6/9 in the left eye. Slit lamp examination showed a right-sided corneal abrasion. Patients with corneal abrasions usually are uncomfortable and photophobic. However, this patient did not seem particularly bothered, so we tested her corneal sensation and found that it was reduced in the right eye. Her face was slightly asymmetrical with ptosis of the right upper eyelid. She had reduced sensation over the ophthalmic and maxillary divisions of her right trigeminal nerve, and anisocoria; the right pupil was 3mm larger than the left pupil. There was no afferent papillary defects and the optic discs looked normal. The rest of her cranial nerves were functioning normally. We questioned the patient in more detail about her medical history. For the past 15 years she had complained of numbness and stiffness on the right side of her face. This had, after some time, been diagnosed as right trigeminal neuralgia. Over the previous 2-3 years friends had mentioned a slight drooping of the right side of her face. She had had no medical tests or treatment.

That was a curious incident - meningioma example

Right-sided parasellar meningioma

As per the above image, cerebral magnetic resonance imaging with gadolinium contrast showed a large space-occupying lesion involving the right stella, cavernous sinus, and the cerebellopontine angle, probably a meningioma, arising from the petrous apex or peri-stellar region . The patient was urgently referred to the neurosurgeons who decided to debulk the tumour. Following surgery, and histological confirmation of a meningioma, the patient developed a complete third nerve palsy with ipsilateral ptosis and myosis, and may have had symptoms from her meningioma for over 15 years, which may have been attributed to trigeminal neuralgia. It is important to take a thorough history and not dismiss persistent, albeit minor, symptoms. We suggest that when no clear cause for a corneal abrasion is found, both the facial and the skin sensation should be checked. Now and again, there may be more than meets the eye!”

What is not present may be more important than what is present.

How can one become a better detective or diagnostician? Please share your insights.

Striving to better detecting,

 

John Mary Meagher

 

References

[i] Vaideanu, D, Fraser K, Deady JP. “Just another Corneal Abrasion?” Lancet 2002; 359: 1916.

 

 

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