The BBC documentary series, the Brain Hospital, followed patients and staff at London's National Hospital for Neurology and Neurosurgery and was always likely to be popular.

For the arguably ghoulish, it offered the chance to watch surgeons delving around inside people's heads, while the backdrop of hospital life revealed some extraordinary medical and emotional stories of patients and staff.

Among these was that of Barbara Cullen, a teacher who first started getting severe headaches three years ago, around Christmas, which she initially attributed to "yuletide excess," and the operation which cured her.

Carried out by Laurence Watkins, the UK's only surgeon to offer this technique, it involves implanting two electrodes in the back of the head, while the patient is awake, and then connecting these to a pacemaker-like stimulator implanted in the abdomen. The reason Ms Cullen had to be awake during the operation was so she could report on the progress of "a tingling sensation" and hence enable Mr Watkins to position the stimulating electrodes correctly. The surgery worked, and two months after leaving hospital Ms Cullen was back surfing, her sporting passion.

For all the human and scientific excitement generated by the series, for the Brain and Spine Foundation (BSF), the UK's only generic neurological charity which offers advice and support for professionals and patients across the spectrum of neurological conditions, the heightened awareness brought by the series has been a mixed blessing.

Viewers with concerns were referred by the BBC Action Line to the foundation's helpline, and, as its chief executive, Maggie Alexander, explains: "We really came into our own, in that people whose query wasn't disease-specific had somewhere to turn. We had calls from people with medical concerns, like brain tumours or cluster headaches, but also more general queries about, for example, stem cell treatment. But beyond that, there was also a host of essentially non-medical topics - lack of support and information from GPs, the length of time for investigations, or people calling because they can't get referrals to appropriate specialist centres because of problems with local health service budgets."

Ms Alexander added that: "On the whole, callers have been pretty desperate". This situation might not surprise Neil Kitchen, associate clinical director at the National Hospital, and one of the UK's small band - only about 110 - of steady-handed neurosurgeons.

The man shadowed by Ian McEwan when researching his acclaimed novel, Saturday, about a successful neurosurgeon, Mr Kitchen was recently interviewed in the British Medical Journal, and asked to cite the worst things about his career. He said these included the inability to substantially help many patients with certain types of brain disease or injury, but also "bed shortages, particularly in neuro-critical care" and "a constant balance between dealing with urgent cases and fulfilling the needs of elective patients, many of whom require large procedures. In the end it comes down to limited resources, human and otherwise, in what is a very small specialty compared with those many of my colleagues are in."

It is somehow surprising that Mr Kitchen refers to his specialty as "very small" - given the fact that neurological conditions are this country's most common cause of serious disability. 1% of us are newly diagnosed with a neurological condition every year, 10 million people live with one, they disable about a million and leave 350,000 needing help for most daily activities.

Despite this high human tally, the BSF, set up in 1992 by neurosurgeon Peter Hamlyn - the man credited with saving boxer Michael Watson's life after his fight with Chris Eubank - is largely dependent on voluntary donations. And it has long found it easier to raise funds for new projects than to support its core functions.

A problem common to many charities, this means that services such as the helpline, for which there is such clear need, can only open 25 hours a week.

As Ms Alexander says: "It's more appealing for a trust or company to fund, for example, our new and undeniably important children's work [Headstrong, a project which is involving parents, children and professionals in developing information resources for young people] than to give us £50,000 a year to keep the helpline going.

"Larger or condition-specific charities have an easier time in that they tend to receive donations from individuals or legacies which tide them over. For us, the largest source of unrestricted funds is the London Marathon. It makes me sad to say it, but all in all, between the supporters who run this for us and the efforts of our fundraising staff, people end up expending huge energies for relatively small, albeit absolutely vital, sums.

Since its launch in 1998, the award-winning helpline, which is staffed by specialist neurological nurses, has responded to over 20,000 calls, while the trust's website has more than 3,000 users a month, and this number is rising rapidly.

On realising this article might yet again raise awareness of and demand on the helpline, Ms Alexander says: "The Helpline manager Angela Collett is understandably apprehensive about the possible impact on her staff if there's a further upsurge of calls. Of course it's what we're here to do, and it's certainly what we want and ought to be doing, it's just hard, some days, to see how we can."

· The Brain and Spine Foundation helpline is open Monday to Friday 9am-1pm: 0808 808 1000.