BACKGROUND

Prostate cancer is the most commonly diagnosed cancer in British men.1 Bone is the most common site of spread from prostate cancer, with vertebral bodies, pelvic bones, femur and ribs frequently involved.2 The base of the skull is a less frequent site of metastasis but is nevertheless very important, both clinically and prognostically, as it can cause a number of cranial nerve dysfunction syndromes.3

Unfortunately, such cases have been poorly documented in the medical literature. We present a patient with occipital headache and hypoglossal palsy as the initial manifestation of prostate carcinoma.

CASE PRESENTATION

A 71-year-old retired man presented to hospital with a history of a sudden-onset deviation of the tongue to the right. On further questioning he reported having had localised pain in the right occipital region 2 weeks before the development of the tongue deviation. He also noticed dysarthria and dry mouth without any history of limb weakness, dysphagia, nasal regurgitation or visual symptoms.

The headache was localised to the occipital region and radiated up to the top of the head, was moderately severe and was worst at night. Significant past medical history included hypertension, rate-controlled atrial fibrillation and resection of a villous adenoma of the rectum several years earlier.

On neurological examination, the patient had signs consistent with right-sided lower motor neuron hypoglossal palsy (fig 1).The remainder of the neurological examination, including a fundus examination, was unremarkable.

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Figure 1

Patient’s photograph, showing deviation of the protruded tongue consistent with right lower motor neuron hypoglossal palsy.

INVESTIGATIONS

Initial investigations included a CT scan of the head and x ray of the cervical spine, both of which were reported normal. Routine laboratory parameters including full blood count, urea and electrolytes, and liver function tests were within normal limits. The patient was sent home with an request for an outpatient MRI of the head and referral to a neurologist. Two days later the patient wrote to one of us (RP) enclosing a copy of a report, entitled “occipital condyle syndrome”,4 printed from a web search and asked for a whole-body scan to be performed on him to exclude underlying metastatic disease. Further investigations carried out revealed an elevated PSA at 137 mcg/l, a chest x ray showing metastasis to the right 3rd and 5th ribs, and a bone scan revealing extensive skeletal metastasis throughout the pelvis, spine, ribs, proximal long bones and base of the skull (fig 2). A contrast MRI scan of the head and base of the skull showed abnormal signals in the right occipital condyle, with widening compatible with local metastasis (fig 3). A transperineal needle biopsy of the prostate confirmed the diagnosis of poorly differentiated adenocarcinoma of the prostate, with a combined Gleason score of 5+5.

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Figure 2

Isotope bone scan from behind, showing metastasis to the skull base (black arrow) along with extensive bony metastasis.

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Figure 3

MRI of head and skull base: coronal postcontrast T1 image showing abnormal signal in the right occipital condyle (white arrow) compatible with local metastasis.

TREATMENT

The patient was initially treated with the oral antiandrogen bicalutamide and tapering doses of dexamethasone. Currently he is being treated with the depo injectable gonadorelin analogue leuprorelin every 3 months.

OUTCOME AND FOLLOW-UP

Seven months after the diagnosis, the patient feels much better and the headaches have resolved, although he continues to have tongue deviation and slight speech difficulty. He does experience hot flushes as a side effect of leuprorelin.

DISCUSSION

Occipital condyle syndrome (OCS) consists of unilateral pain in the occipital region along with an ipsilateral paresis of the 12th cranial nerve (hypoglossal nerve) and is typically due to skull base metastasis. The hypoglossal nerve arises from the motor nucleus located beneath the floor of the fourth ventricle, passing in front of the vertebral and posterior inferior cerebellar arteries. It exits the base of the skull through the hypoglossal canal in the occipital bone; it then traverses the neck and curves back, divides and innervates the tongue muscles.

Metastasis to the skull base is a frequent complication of various systemic cancers.5 In the largest published series of 12th nerve paresis, tumours, predominantly malignant, produced half of the palsies. Trauma, infection, stroke and Guillain-Barré syndrome account for the remainder of cases.6

OCS has been described as a manifestation of metastasis to the skull base in several retrospective studies; however, in most such studies OCS was a manifestation of a known primary malignancy.3^,4^,7^,8

In the largest reported series on OCS,4 of 11 patients reported, 9 had a known primary cancer, breast cancer being the most common malignancy in women (2/3) and prostate cancer, the most common in men (4/8).In two of these patients, OCS was the initial manifestation of metastatic cancer. There has been a single case report previously published on OCS as the initial manifestation of metastatic prostate cancer.9 For patients with suspected skull base metastasis, MRI is the imaging modality of choice.10^,11 A high-quality CT or a radionuclide bone scan may complement MRI.11^,12

Prostate cancer with metastasis to the skull base carries a poor prognosis; in two different reviews published, the median survival from the time of cranial nerve involvement was 3–4 months.7^,8 Interestingly, patients who had a cranial nerve palsy as the initial manifestation of an underlying prostatic malignancy were reported to be alive at 18 months9 and 42 and 84 months8 after the diagnosis in two reviews on skull base metastasis in prostate cancer.