The patient: A 29-year-old man in India

The symptoms: The man, a fighter pilot in the Indian Air Force, went to a civilian neurologist after having persistent headaches for 18 months. The headaches would occur approximately two to three times per month, starting in the late afternoon and lasting up to three days. Sleep did not improve his symptoms.

The pain was typically greater on the right side of his head, but he would often feel pain on the left side as well. The pilot also reported that just before a headache, he would experience a "sense of lousiness," his doctors wrote in a report of the case.

Sometimes, the pain was so intense that the man was unable to take part in scheduled flights. If he flew anyway during an episode, his headache would be even worse the next day.

What happened next: According to the man, his finances and personal relationships were not a source of stress. (Stress, in general, is a very common headache trigger.)

When asked about his medical history, the pilot recalled no recent ailments or conditions that could cause recurring headaches, such as inflammation and congestion of the sinuses (sinusitis). He had no family history of chronic headaches or migraine, a neurological disease that frequently causes moderate to severe headache, among other symptoms. Nor did he experience nausea, vomiting or visual anomalies called "auras," which often accompany or precede migraines.

Nevertheless, the civilian doctor determined that migraines were the culprit. He prescribed divalproex ‪—‬ an oral medication used for migraine prevention — and told the patient that he would likely need this medication for years. Concerned about taking the drug over a long period, the pilot decided to consult an authorized specialist at a military medical facility for further evaluation.

The diagnosis: The military doctors reviewed the pilot's case and examined him. All of his test results were in the normal range, and a CT scan showed no brain abnormalities. They ordered a nasal endoscopy — an exam that uses a camera to examine the nasal cavity and sinuses — and found that the patient had a deviated septum. However, the deviation was so minor that they ruled it out as a possible cause of his pain.

Finally, the doctors agreed with the initial diagnosis: The pilot was experiencing migraines. The causes of migraine are not fully understood, although genetics and environmental factors may contribute to both the duration and intensity of migraine pain in a given individual.

The treatment: The pilot was given the migraine medicine sumatriptan, to be taken at the first sign of pain, and aspirin, to be taken during headaches. He was allowed to continue flying under restricted conditions, and he had to report to a military neurologist for monthly reviews over the next three months.

Four months later, he was headache-free and had stopped taking medication, according to the report. However, his superior officers needed a detailed medical review before they could restore his unrestricted flight status, as severe migraines can disqualify pilots from flying.

Over three days, doctors conducted in-depth interviews with the pilot, focusing on the first appearance of his symptoms and the circumstances leading up to his headaches. They were puzzled by certain details: His lack of nausea, vomiting and auras, and the fact that he got no relief through sleep. These facts raised questions about the migraine diagnosis.

During the interviews, the pilot recalled that his headaches began around the time that he started using a new type of helmet with a tighter fit. The headaches corresponded with days in which he flew multiple flights and became worse the longer he wore the helmet. Then, around the time he started taking the prescribed medication, he coincidentally received a new allotment of personal flying clothing — including a helmet that was the correct size — for a new plane assignment. His headaches suddenly stopped.

"At that point the officer did not connect the cessation of headaches with the use of the new helmet," the doctors reported. "Reviewing the case in its entirety, the diagnosis of migraine or vascular headache was found to be incorrect; instead the individual was suffering from external compression headache due to an ill fitting helmet."

Compression headaches are caused by tight external pressure on the scalp and forehead, and they typically resolve when the pressure eases.

Doctors instructed the pilot to keep a headache diary and scheduled follow-up visits to confirm their findings. Five months later, his headaches had not returned, as he'd continued using the better-fitting helmet.

What makes the case unique: When the military doctors scoured peer-reviewed studies, they found no reports of similar instances of compression headache "in any of the Air Forces of the world," they wrote in the report.

This case, they added, emphasizes the medical significance of making sure that pilots' flight uniforms — especially their helmets — fit properly.

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

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The patient: A 55-year-old man in Bangladesh

The symptoms: The man went to the emergency room with severe abdominal pain that he said began five hours prior to his visit.

What happened next: During a physical examination, doctors noted that the patient's temperature and blood pressure were normal. His heartbeat was slightly elevated, at 110 beats per minute (bpm). (A typical resting heart rate for adults is 60 to 100 bpm.)

The man explained that one day earlier, an eel had "entered through his rectum accidentally," his doctors wrote in a report of the case. At the time of the encounter, the man was wearing a lungi — a type of long skirt often worn by Bangladeshi men — and he explained that the eel entered his lungi through the opening at the bottom and then wriggled into his anal canal.

He did not seek medical attention immediately after this happened, as he had hoped the fish would exit on its own.

When the doctors kneaded the patient's abdomen, it was rigid and tender. They ordered an X-ray, which revealed a dark, eel-shaped shadow on the right side of the abdomen.

The diagnosis: The X-ray showed a crescent-shaped gas shadow under the right part of the man's diaphragm and hinted that he had developed peritonitis — inflammation of a membrane called the peritoneum, which covers the abdominal organs. Peritonitis is usually caused by a bacterial or fungal infection, but it can also develop if fluids from other organs leak into the peritoneum.

If the condition is not treated quickly, it can lead to a life-threatening infection that can spread rapidly through the body.

The treatment: Doctors administered IV antibiotics, as well as fluids and anti-ulcer medications, which help repair injuries to organs' outer mucosal layers and prevent deeper tissue damage.

Due to the peritonitis, the doctors determined that the patient was at risk of septicemia, or "blood poisoning," in which pathogens invade the bloodstream. They decided to operate on the patient immediately and remove the eel via a laparotomy, a surgical technique that creates an opening in the abdominal wall and provides access to the pelvic organs.

After making an incision in the man's sigmoid colon — the S-shaped section of the large intestine adjacent to the rectum — the surgeons extracted the eel from the peritoneal cavity, the space surrounding the abdominal organs and encased by the peritoneum.

The eel measured nearly 2.2 feet (0.6 meters) long and was still alive. Perhaps, the doctors hypothesized, the eel was able to continue breathing by punching through the wall of the man's colon and squeezing into the peritoneal cavity, which contains a pale-yellow fluid that reduces friction between organs. This peritoneal fluid is mostly water, but it also contains glucose, electrolytes, proteins, enzymes, white blood cells and urea, a compound found in urine.

The surgeons then performed a sigmoid colostomy, creating an opening in the abdomen as an exit point for contents of the man's large intestine. In this way, they bypassed the damaged section of sigmoid colon to prevent leakage of fecal matter that could lead to further infection. Four days later, the man was symptom-free and was discharged from the hospital. The report did not document any follow-up visits.

What makes the case unique: Traumatic perforation of the intestine by foreign objects is uncommon, and cases involving live animals are "exceedingly rare," the authors wrote in the report. However, foreign objects often find their way into the human body through accidental ingestion or deliberate insertion into the rectum. Some deliberately inserted objects, such as vibrators, are designed for this purpose. Others are not; these have included chicken bones, light bulbs, metal rods, glass bottles and kitchen whisks.

Penetration of the colon by a live fish is an "unusual and scarcely documented event," the man's doctors added in the report. They noted one reference to such a case that appeared previously in scientific literature and involved a 50-year-old male patient in Hong Kong. In that case, the man knowingly inserted the eel — which measured more than 1.6 feet (0.5 m) long — into his rectum, allegedly in an attempt to relieve his constipation.

This article is for informational purposes only and is not meant to offer medical advice.

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