A desperate mother has to watch in horror as her daughter becomes paralysed every other day. Sarah Firth, 39, watches while her daughter is unable to move a single bone in her body for up to 19 hours at a time. In this state Ms Firth's daughter, Mia Park, can only cry out for help and wait until drugs help her regain movement. Mrs Firth said: 'When it happens, it is absolutely horrendous. My little girl goes from being an energetic youngster to being trapped in a body that can't move. 'It is awful to watch. She is so frightened. Her eyes are full of fear as she desperately waits to feel any form of sensation again.' Sarah Firth, 39, has to watch helplessly as her daughter, Mia Park, 12, becomes paralysed every other day to a rare genetic condition . Mia has hypokalemic periodic paralysis which means she has periods where she can't move her body and has to be rushed to hospital (pictured) Mia, who is just 12, suffered her first petrifying episode of paralysis in January this year. Ms Firth, a nurse, said : 'She had woken up in the night complaining she couldn't feel her arm. I just thought she had slept on it and it had gone numb. 'But by the morning, Mia said she couldn't feel her arms or legs. Initially I thought she was winding me up and trying to get the day off school because it was snowing. 'It was only when she couldn't sit up, or even move, that I realised she was telling the truth. 'I knew she hadn't had a stroke as her face wasn't sloping but I knew something very serious was wrong. 'I used a needle to prick her fingers and toes and she didn't flinch a single inch. I felt absolutely terrible for doubting her. She looked so scared. I could see she was desperately trying to move her arms and legs but couldn't. 'I immediately dialled the NHS helpline who sent for an ambulance. 'It was only as paramedics were carrying out an ECG and checking her blood pressure and airways that it struck me what was wrong. Hypokalemic periodic paralysis is a disorder that causes occasional episodes of muscle weakness and sometimes a lower than normal level of potassium in the blood. The condition is caused by a mutation on chromosome 17. In most cases, it is passed down through families (inherited) as an autosomal dominant disorder. In other words, only one parent needs to pass the gene related to this condition on to you in order for you to be affected. Symptoms include attacks of muscle weakness or loss of muscle movement (paralysis) that come and go. There is normal muscle strength between attacks. Attacks usually begin in the teen years, but they can occur before age 10. How often the attacks occur varies. Some people have attacks every day. Others have them once a year. During attacks the person remains alert. The weakness or paralysis: . Other symptoms may include: . Source: US National Library of Medicine . 'My ex-husband, Mia's dad, and her grandad, also suffered from a condition that intermittently left them paralysed.' The extremely rare and potentially fatal condition, hypokalemic periodic paralysis, is caused by dangerously low levels of potassium. It took four paramedics to safely lift Mia, who had become a dead weight, onto a back board and into an ambulance. After initially being taken to Barnsley General District Hospital, she was rushed 20 miles to Sheffield Children's Hospital. It was there her potassium levels were checked and results showed they were extremely low and a neurologist, Dr Chris Rittey, diagnosed Mia with the debilitating condition. Mia was given potassium intravenously, but only after an agonising 14 hours, did she slowly regain movement. Ms Firth, a single mother, from Barnsley, South Yorkshire said: 'We were both just so relived. I never thought I'd be so happy to see Mia wriggle her fingers and toes. 'It is something you just take for granted, never imagining your child will literally freeze in her sleep, and lose sensation of almost every muscle from her neck down.' Over the following week, Mia fell into a state of paralysis every other day, each time it starting in her sleep. Ms Firth, 39, said: 'Every second morning she would wake up unable to move. Each time we were terrified. 'All we could do was wait for the IV potassium to flow through her body and pray it would take effect.' The condition, caused by mutation of chromosome 17, only effects one person in every 100,000 and is far more common in men than women. Ms Firth continued: 'That's why it never initially occurred to me that's what Mia had. Her dad had always told me it was a condition that affected males, not females, but obviously it does happen in girls too. 'Although Mia's attacks have slowed down to every couple of weeks at the moment, we have been warned the bouts of paralysis can happen at any time and could get more frequent. They generally happen when she is sleeping. 'If it happens when she is awake, Mia starts to slowly feel a tingling sensation in her fingers and she knows it's about to happen, and can take a form of potassium syrup to stop it developing. 'But when it starts in her sleep, she has no idea, and wakes up completely paralysed. 'It has had a devastating effect on our lives. I can't allow Mia to sleep over at friend's houses, something girls her age take for granted, or go on an overnight school trip without me in case she has an attack. 'As soon as it happens we have to get her straight to hospital in an ambulance so she can be treated immediately. If we don't we could lose Mia. Mia's attacks usually occur in her sleep, and she wakes up paralysed. Her mother must feed her, wash her and put a bed pan underneath her. In between attacks she can move normally . Mia was once paralysed for 19 hours. She finds relying on her mother difficult as she wants to be independent. She cannot stay at her friends houses in case she has an attack in her sleep . 'When it initially started I asked the consultant if it could be fatal, it broke my heart when he said yes. It's is horrendous to think I could lose my daughter. It's every parent's worst nightmare. 'It's very hard watching her go to sleep. I often check on her two or three times a night to see if she is moving. 'Every morning the first thing I do is check she can move hers arms and legs, only then do I breathe a sigh of relief. 'But of course there are times when she wakes up and is frozen to her bed. She is like a statue, completely still apart from her face.' The longest episode Mia has suffered has lasted 19 hours. Ms Firth said: 'During that time I have to feed her, wash her and put her on a bed pan. 'It's very frustrating for her. She's a young girl, just about to hit her teenage years and doesn't want to feel so out of control and dependant on me. 'She tries her best to put on a brave face but I know it's extremely hard for her. 'And because Mia is up and about a lot of the time and maintains a normal lifestyle as such, people do not realise how poorly she is and the severity of her illness. 'It can be a fatal if we don't act quickly.' Ms Firth and her daughter have no idea what the future holds and how much the condition will take over their lives. But they are taking each day as it comes and trying to remain positive. During an attack, Ms Firth is rushed to hospital where she is treated with potassium through an IV drip (she is pictured in hospital, left and right) Ms Firth added: 'We just have to take it in our stride and hope that we can manage the condition.' She is now fundraising for the Sheffield Children's Hospital Make It Better appeal, to build a new wing including plenty of private bedrooms so families can stay together at difficult times. When Mia was in hospital, Ms Firth kept vigil at her bedside, sleeping in a high-back chair. In the new wing, she would have her own pull-down bed, Mia would have more privacy, and would get better more quickly in a hospital designed with children in mind. David Vernon-Edwards, director at The Children's Hospital Charity, said: 'Mia is an inspirational girl, fighting a terrifying illness with such bravery. 'We are so lucky to have the specialist consultants at our hospital, such as Dr Rittey, who can help treat and control this condition. 'That is why we need to raise money for this appeal, to keep our specialist services special and bring world-class facilities to our already world-class hospital.'
Mia Park, 12, has a genetic disorder called hypokalemic periodic paralysis . Causes muscle weakness and she becomes paralysed every other day . Has to be rushed to hospital where she is given potassium via an IV drip . Episodes often happen in her sleep and she wakes completely paralysed . Condition is genetic and only affects one person in every 100,000 .