Skull base map

Written 8 September 2026, updated twice on 16 September 2026: first for the Southampton appointment, then again the same morning after her partner set out the full eighteen month history, which corrected one entry and added another. Both corrections are marked below rather than folded in silently. From the imaging report as relayed (the written report has still not been seen) and standard anatomy. Sources by PubMed ID (PMID) and NCBI Bookshelf chapter number (NBK); the full thread is em-research/17.

Read this before the rest of the update

Nothing here measures the tumour. The last scan is the MRI of 2 September. Every change in this update comes from symptoms reported since 8 September, not from an image. The pattern of those symptoms is what forward growth into the sinus and nasopharynx, and rising pressure inside the head, would look like. That is an argument for a repeat scan, not a substitute for one. Anywhere below that says a structure is now involved, read it as "the signs point here, and here is the test that would settle it".

Two other things that keep the map honest. Several of the new symptoms are almost certainly not the tumour at all, and they are listed as such rather than quietly left out. And one of the most important new items is not new at all: the pressure-on-straining sign turns out to have been present since about mid August, which changes the timeline rather than adding to it.

The one thing to hold onto

A chordoma grows in bone and presses on the brain and nerves from outside. It does not grow into brain tissue the way a glioma does. So the question "which parts of the brain are affected" means "what is it pressing on", and the answer can be read off the anatomy.

What has changed since 8 September

1. The forward direction now has the most new evidence. On 8 September the blocked right nostril was a single "possible". Since then there have been five more local signs, all pointing the same way: pain behind the nose (10 September), a right ear hum on waking (10 September), nose pressure worse lying down (11 September), a metallic blood taste lasting five minutes with nasal pressure alongside it (11 September), and a recalled sensation of fluid in the nose (11 September). One of those is a shrug. Five in five days, all on the same axis, is a direction of travel. The sphenoid sinus and the back of the nose move from "possible" to the best-supported new extension, and the right ear hum adds a structure that was not on the map before: the eustachian tube, whose opening sits in the side wall of the nasopharynx, immediately below and in front of the clivus.

The five-minute blood taste is the one to say out loud. Seconds-long metallic tastes are a drug and nerve phenomenon; five minutes with nasal pressure fits material actually present and draining back where she can taste it.

2. The raised-pressure explanation for the left sixth nerve palsy got stronger, and older. On 15 September she reported that straining brings on head pressure and dizziness, and that this has been happening for over a month, so from about mid August, around when the double vision began. Head pain and dizziness on straining is a recognised sign that pressure or fluid flow at the back of the skull is affected. On 8 September the left sixth nerve palsy had two candidate causes with nothing to separate them. It still has two, but the pressure branch now has independent support from a symptom that predates the palsy. This raises the priority of looking at the back of her eyes. It does not lower the priority of the scan: both causes remain live and they are not mutually exclusive.

3. CORRECTED. The jaw is not a new territory. Earlier on 16 September this section read that increased right jaw sensitivity on 12 September might mean the tumour reaching below the cavernous sinus. Her partner's account of the history, given the same morning, records jaw pain alongside the headaches by late 2025. So the jaw has been symptomatic for about a year, and 12 September was worsening rather than onset. That reads in the opposite direction from a recent spread.

What it does say is worth more than what it took away. The jaw is the third division of the trigeminal nerve, and it is the one division that does not run through the cavernous sinus: it leaves the skull through its own hole lower down (NBK482283, NBK532976). Sparing of that division is what localises a trigeminal problem to the sinus. Two divisions symptomatic in 2025, the eye and the jaw, therefore point back at the ganglion in Meckel's cave, which sits against the clivus, rather than at the cavernous sinus alone (PMID 8786827). That is a localisation to the tumour's own site from an early date. The open question for the examiner is which parts of her face are numb, as opposed to painful.

3b. ADDED. The lower cranial nerves move from green to amber, on history rather than a new symptom. A private osteopath in May 2026 noticed that her voice sounded unusual and referred her back to the doctor for a thyroid check. Until 16 September this map recorded the lower cranial nerves as not involved on the grounds that no voice change had been reported. One had been, four months before diagnosis, and it came from a stranger with no reason to imagine it. The nerves to the voice box and palate leave the skull immediately below the clivus. The character of the voice decides what it means, and it points three ways: hoarse or breathy is the nerve to the voice box; nasal, as if speaking through a cold, is the palate and would fit the nasopharyngeal extension above; quiet or effortful but otherwise unchanged is pain, morphine and exhaustion, which is the likeliest single answer. Swallowing is normal and the tongue does not deviate, which is why this is amber and not red.

4. Three things that look alarming and are not the tumour. The rectal bleeding on 12 September is drug induced proctitis from the diclofenac suppositories, which have been stopped. The ten seconds of tingling in both lips and tongue on 11 September was bilateral and with full awareness, which is the metabolic and drug pattern rather than the seizure pattern. The worsening reading vision in the left eye on 9 September came with intact colour and fields, so it is focus and blur on the new sixth nerve palsy rather than the optic nerve. Saying which symptoms are not tumour is part of the map.

5. Two more that are watch-items rather than map changes. Hiccups with a taste of vomit (12 September) are almost certainly reflux with slow stomach emptying on morphine; they matter only because the lowest part of the brainstem drives the hiccup reflex, and the discriminators that would make it a brainstem sign, trouble swallowing, choking on liquids, a hoarse voice, are all still absent. Pain all down the back (13 September) is most likely mechanical after days largely in bed, but new back pain in someone with a probable malignant bone tumour is a red flag for spinal involvement until shown otherwise, so it stays on the list.

The clivus and its neighbours

The clivus is the sloping bone at the centre of the skull base, behind the nose and in front of the brainstem. Six directions:

• In front: the sphenoid sinus and the back of the nose. Growth this way causes nasal blockage and a feeling of fullness (PMID 19193749). Now the best-supported new direction, on the five signs above. Nasal endoscopy answers it.
• In front and below: the nasopharynx, the space behind the nose and above the palate, and in its side wall the opening of the eustachian tube, which drains and ventilates the middle ear. A mass here blocks that tube and the ear fills with fluid: in an adult, a one-sided middle ear effusion is a recognised red flag for a nasopharyngeal mass and is the classic pitfall when it is not investigated (NBK538293). Her right ear hum on 10 September is on the same side as the blocked nostril. A brief hum on its own is not glue ear and must not be inflated into it; the point is that this is now a structure with a cheap test attached. Looking in the ear and a tympanogram settle it in two minutes.
• Behind, across a thin layer of spinal fluid (the prepontine cistern): the basilar artery and the pons, the part of the brainstem that carries the wiring to the arms and legs, controls balance, swallowing and speech, and keeps a person awake. The report says the tumour reaches into this fluid space and partly wraps the artery. Nothing in her signs says the pons itself is compressed. The cistern is also part of the spinal fluid pathway, which is where the straining sign belongs.
• Each side: the cavernous sinus, a pocket of veins through which the internal carotid artery and four nerves pass: the third (lifts the lid, moves the eye in, up and down, and controls the pupil), the fourth (moves the eye down and in), the sixth (moves the eye outward) and the two upper branches of the fifth (feeling in the forehead, cheek and upper teeth). The report puts the tumour in the right cavernous sinus and against both carotids.
• Below and to the side: Meckel's cave, where the trigeminal nerve has its ganglion, and below it the foramen ovale carrying the jaw division out of the skull. Not reported involved; the right jaw sensitivity of 12 September is the only thing pointing this way and it points weakly.
• Above: the sella and pituitary gland, and above that the optic nerves and chiasm. Not reported involved.
• Below: the canal for the tongue nerve and the opening for the nerves of swallowing, voice and shoulder. Not reported involved.

The nerves, and the patient's signs in order

Her sequence, fifth nerve pain, then third, then fourth, then the opposite sixth, is the expected order for a tumour in the upper clivus growing into the right cavernous sinus and back across the cistern. In published series of clival chordoma, double vision is the presenting complaint in about a third and a sixth nerve palsy is found in nearly half (PMIDs 28409727, 25594191). The newer signs add a forward axis to that picture, into the sinus and the nasopharynx.

What is not involved, and the sign that would say it was

• Pons and brainstem. Watch for: weakness of an arm or leg, unsteady walking, slurred speech, coughing on drinks, facial weakness, drowsiness that does not follow the dose pattern. None present.
• Lower nerves and the lowest brainstem. NO LONGER FULLY CLEAR. Swallowing is normal and the tongue does not deviate, but a voice change was noticed by an osteopath in May 2026 and was never followed up as a neurological sign. Watch for: trouble swallowing, choking on liquids, a hoarse or nasal voice, the tongue pointing to one side when stuck out. The hiccups of 12 September are watched here rather than counted here.
• Optic nerves and chiasm. Watch for: dimming, red looking washed out in one eye, loss of the outer edges of vision. None present; the 9 September reading change had intact colour and fields. A recorded acuity and field test gives the baseline.
• Pituitary and hypothalamus. Watch for: passing large volumes of dilute urine with thirst, exhaustion out of proportion, sodium out of range. Endocrinology reviewed her on 3 September; page 1 of the Treliske summary with the bloods is still unseen.
• Temporal lobe. Watch for: a warning feeling, lip-smacking or fiddling movements, not responding, confusion afterwards. Not described.
• Spine. Watch for: a band of numbness, weakness in the legs, trouble passing or holding urine. None present; the back pain of 13 September is most likely mechanical.
• Spinal fluid pressure. The prepontine cistern is part of the fluid pathway. Watch for: headache worst on waking, vomiting, increasing drowsiness, and the sixth nerve sign already discussed (NBK482119). The straining sign belongs here and is now on the record.

The arteries

The basilar artery is partly wrapped and both carotids are abutted. Wrapped is not blocked. For daily life this is not a risk that changes anything; for the surgeon it is the central planning problem. Encasement of the basilar lowers the chance of complete removal (13 percent against 42 percent in one skull base series, PMID 23451716) because surgeons leave a sliver of tumour on the vessel rather than risk it, and carotid injury in endoscopic chordoma surgery runs at about 2 percent in the largest series (PMIDs 23695646, 31226887). This is the argument for a high-volume centre and for the surgeon's own numbers.

What to ask at the appointment

Five, in order, and the first three are cheap.

0. Listen to her voice and look at her palate. Ask her to say "kuh kuh kuh" and then hold "ahhh": a palate that does not lift, or a hoarse or nasal sound, is a lower cranial nerve sign, and one was noticed in May 2026 and never chased. Free, and it is the oldest unexamined sign she has.
1. Look at the back of her eyes. Swollen discs would settle the raised pressure question that the straining history has now put on the table, and it takes a minute.
2. Look in the right ear and do a tympanogram. A one-sided middle ear effusion in an adult is a recognised red flag for a nasopharyngeal mass, and it is a two-minute test.
3. Nasal endoscopy. It answers the blocked nostril, the pain behind the nose and the five-minute blood taste in one look, and it is the same route any biopsy would take.
4. A repeat MRI, and say what has changed. The last scan is 2 September and six new local signs have appeared since. The specific asks: has the forward extension into the sphenoid sinus and nasopharynx progressed, is the eustachian tube involved, is the third division of the trigeminal nerve or Meckel's cave involved, and is there any sign of raised pressure or of a spinal fluid leak.
5. Test any nasal fluid if it ever runs rather than is felt. Beta-2 transferrin identifies spinal fluid. This is only if it happens; the sensation alone does not justify chasing it.