Now appears to be open access and a good read —
I continued to experience unrelenting tongue pain and vertigo with every step. I was also very depressed and disappointed, so I wrote an irate letter to the neurosurgeon, worried about a cranial nerve injury. “It is inconceivable,” he wrote back, “that the pain in your tongue is related to your stroke since that is like the other side of the continent.” His words, not mine. He then refused to see me ever again in follow-up. He never diagnosed a functional neurological disorder, but he implied it in his letter.
As part of my rehabilitation program, I was required to meet with a psychiatrist and a psychotherapist twice a week. They saw that I was very angry and noted that the pain in my tongue had started after the trauma I had experienced with the stroke. They suspected a factitious disorder related to my anger and desire to gain attention from the neurosurgeon and neurologist. The psychiatrist started me on duloxetine for depression and escalated it to very high dose. It had no effect except to worsen my vertigo. She wanted to start me on a “mood stabilizer” but I refused. I was convinced that my pain was organic.
[...]
On most days, I was resigned to believing my psychiatrist, that the tongue pain was a somatic reaction to my anger. But on other days, I was haunted by the fact that the pain was unilateral. I saw several other neurologists including one who sent me to a pain class taught by a psychologist.
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Finally, 5 years after the surgery, I consulted with yet another neurologist (the tenth? the eleventh?) – a brainstem expert. She personally scrutinized the most recent MRI and saw gliosis of the middle cerebellar peduncle. It was identical to the 1-year postoperative MRI. She could see that traction from that lesion was affecting the principal trigeminal nucleus and distorting the spinal trigeminal sensory tract of the medulla, affecting lingual sensation. She reviewed the imaging with me but stopped short of ordering another MRI with fine cuts because it would not change the diagnosis, prognosis, or treatment. My symptoms of unilateral tongue pain and persistent vertigo were at last explained by a neuroanatomical lesion that could be seen on imaging. The findings of the brainstem neurologist were later confirmed by a neuroradiologist who also saw elongation and thinning of the facial nerve and of the vestibulo-cochlear nerve though both were clinically silent. He also saw a thin trigeminal nerve on the right, consistent with Wallerian degeneration.
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I look back at my experience and wonder how often doctors explain neurological disease as psychiatric illness. Shockingly, neurologists did not seek a structural basis for my symptoms nor considered it important to pursue this possibility. I am a physician with medical knowledge and experience, and yet this happened even to me.
Discussion
Medical epistemology entails rational, inductive, scientific reasoning following the method first proposed by Descartes. Medical epistemology requires evidence from the subjective experience of the patient as well as objective evidence from the physical examination and/or laboratory tests, and/or imaging. In my case, vertigo and unilateral tongue were my subjective complaints, and objective evidence had to come from neuroimaging. The practice of neurology lies in interpretation of subjective complaints in order to know where in the brain to look for a neuroanatomic lesion. Without any objective evidence in my case, my diagnosis was “functional neurological disorder.” Indeed, differentiating cerebral ischemia from functional neurological symptom disorder can be difficult, especially when conversion disorder makes up one-third of neurology outpatients. When ischemia occurs in the posterior circulation, differentiation is even trickier.
Most of my neuroimaging was performed acutely, before encephalomalacia and gliosis had completed, and not repeated for a year. Even after the 1-year MRI was obtained, neuroradiologists were distracted by my very large injury – encephalomalacia of the right cerebellum with ex vacuo dilation of the fourth ventricle – and missed the adjacent tiny finding – middle cerebellar peduncle gliosis affecting my right trigeminal nerve. Brainstem strokes affecting cranial nerve nuclei are sometimes very small and are particularly hard to see on neuroimaging. In my case, the brainstem neurologist had high clinical suspicion and thus was able to locate the lesion.
Now, in retrospect, it seems obvious that my neurological injuries resulted directly from intraoperative sacrifice of a bridging vein, hemorrhage, perivascular edema, and infarction and indirectly from intracranial hypertension, cytotoxic edema, and cell death. [...]
In my case, right unilateral burning pain resulted from distortion of the right spinal trigeminal tract. The pars oralis is the site where lingual pain fibers run and enter the spinal trigeminal tract. Trigeminal pain of central origin is termed “atypical trigeminal neuralgia” and differs from classic trigeminal neuralgia because the pain is constant and not episodic. This type of pain results from a small, medullary infarction and from a lesion in the middle cerebellar peduncle, reflecting its anatomic proximity to the spinal trigeminal tract and principal sensory nucleus. In contrast, typical trigeminal neuralgia of central origin correlates with lesions higher in the pons and affects the nerve roots of the trigeminal nerve.
Objective evidence, appreciated by sight, is undeniably true. Without any visually discernable evidence, my symptoms were considered psychiatric and not neurologic. But the brainstem neurologist knew where to look even before she examined the MRI because a core principle of neurology is knowing from the complaint where in the brain to look.
