When fever, dizziness point to something more

SINGAPORE – Tan Zi Ting was just six months old when she began suffering repeated episodes of intestinal obstruction – blockages that prevent food or liquid from passing through the small or large intestine – along with other issues such as feeding difficulties and persistent constipation.

When she was taken to hospital, doctors told her parents that she had slow gut motility – a condition in which the muscle movements within the gastrointestinal tract that move food through the digestive process are slowed.

The 23-year-old told The Straits Times that over the years, her symptoms expanded to include a variety of ailments, such as nausea, vomiting and high fevers, often requiring medical intervention.

Her condition meant she could not participate in activities like physical education classes in school, or go out with friends. She sometimes had to miss school altogether.

“Since it’s been there all my life, I kind of thought it was normal,” she said.

When Tan was 13, however, the obstructions became more intense, to the point where she could not walk when they occurred, resulting in her missing more than 40 days of school over the year.

“I think that was when we realised that something was severely wrong, because it wasn’t just something that I could push through any more,” she said.

Another patient, Louisa Lim, began experiencing a persistent fever in 2021, shortly after getting married.

While tests showed that she did not have Covid-19, doctors were unable to determine the cause of her consistently high body temperature, which reached around 39 deg C for months on end, the 34-year-old said.

They diagnosed it only as a pyrexia, or fever, of unknown origin, she recalled, adding that other symptoms – including pain, dizziness and a burning sensation across her back – soon emerged, though tests and scans were unable to identify their cause.

“I kept wondering – if the fever is my body’s way of telling me something, then what is it?” said Lim, who was working in sales at the time.

Diagnosis and relief

Tan, who had been receiving paediatric care at KK Women’s and Children’s Hospital, decided to continue her treatment at the National University Hospital (NUH) in 2021, when she turned 18.

At NUH, Kewin Siah – a senior consultant with the hospital’s gastroenterology and hepatology division – worked with Amanda Chan, a senior consultant from the neurology division, and others from different specialities to piece together the various symptoms Tan was experiencing to better understand her condition.

In 2021, she was diagnosed with small fibre neuropathy (SFN), a form of peripheral neuropathy – a group of conditions in which nerves beyond the brain and spinal cord are damaged or dysfunctional.

Symptoms vary and can be vague. They include painful tingling or burning sensations in the hands and feet, as well as heart palpitations and numbness.

In 2022, following a clinical assessment and confirmatory skin biopsy, Lim was also found to have SFN.

She described the diagnosis as a relief.

“To finally know what it was meant that I could get treatment,” she said.

Chan said that as SFN affects only small nerve fibres, tests for large nerve fibres or the central nervous system can often appear normal.

“It’s very difficult to diagnose because not everybody has access to these small fibre tests, and at the same time, it’s a relatively newly defined condition,” she added.

Siah said that SFN can often be identified only by piecing together the various symptoms a patient may be experiencing.

“Unless you think about it and put the symptoms together, a lot of patients won’t be getting the right diagnosis,” he said.

Chan noted that while current medical literature suggests that SFN is rare – affecting up to 50 people per 100,000 – its prevalence has gone up since the Covid-19 pandemic, with some studies suggesting anywhere between 25% to 50% of people with long Covid have the condition.

“It’s actually much more common than we think,” Chan said.

She added that this could be a result of the immune system going into overdrive when responding to an infectious disease and attacking the small nerve fibres as a result.

Lim said that although she used to be very active – going to the gym up to twice a day – her condition put a stop to her physical activity, and she now relies on a walking aid to get around.

She was originally treated with oral medication to manage her pain, later progressing to intravenous immunoglobulin (IVIG) therapy, which involves the infusion of antibodies from healthy donors.

Though IVIG provided relief, the frequency of infusions was disruptive and its effects short-lived.

Lim said the disruptive nature of the treatments, coupled with brain fog, made it difficult for her to concentrate on her job, and she opted to stop working.

In 2023, she was started on rituximab – a targeted immunotherapy used to treat certain autoimmune diseases and cancers – which helped improve her condition, though her symptoms gradually return between treatment cycles.

For Tan, Siah oversees the severe constipation caused by her condition, working with the colorectal surgery team to develop a treatment plan that has improved her bowel function over time.

Both doctors are also contributing to research on how SFN is treated and understood.

Siah said that while Tan and Lim are faring relatively well, not all patients with SFN are in a similar position, adding that up to 20% “don’t do that well at all”.

Chan noted that in severe cases, the symptoms of SFN could include cardiovascular dysautonomia – a nervous system disorder that results in irregular heart rate or heart rhythms – which could lead to death.

Lim hopes to eventually return to her previous line of work, which she described as “quite fun”, as she frequently travelled for work, though she understands her condition might necessitate something less hectic.

“I’m going to manage my expectations,” she said.

For Tan, learning more about her condition made her passionate about the science behind it, and she is now studying medicine at the University of New South Wales in Sydney, Australia.

She hopes to eventually specialise in gastroenterology, and in November will return to Singapore for an attachment at NUH.

“I think my condition gave me a very strong sense of purpose to be a doctor who shows patients that there is life beyond their diagnosis,” she said.