Lumbosacral transitional vertebra and thoracic limb malformations in a Chihuahua puppy.

A three-month-old, male Chihuahua puppy with congenital absence of the distal 40% of the right thoracic limb was examined. The limb ended as a short, rounded, skin-covered stump. Radiography revealed a 40% shortened humerus tapered to a blunt end without its distal extremity. Dissection of the left thoracic limb identified luxation of the elbow joint and absence of the fourth digital pad. Alizarin-red staining and clearing demonstrated syndactylous fourth and fifth digits in the left thoracic limb and an anomalous eighth lumbar vertebra. This additional vertebra was unilaterally sacralized and constituted a lumbosacral transitional vertebra.

Development and variation of the lateral vertebral foramen of the atlas in dogs.

Postnatal development and variation of the bony cranial border of the lateral vertebral foramen (LVF) of the atlas was studied in 96 dogs. Developmental ossification was investigated in 8 known-aged Miniature Schnauzer pups, after each atlas was prepared either as an alizarin-red stained clearing or as a dried cleaned bone. Variation was investigated in 63 atlases from mature dogs and by study of radiographs from 25 mature dogs of various breeds. The soft tissue structures passing through the LVF and attaching to its cranial border were dissected in an additional 2 embalmed and 2 fresh cadavers. In 2-week-old pups, the LVF was represented by a notch in the cranial margin of the bony arch of the atlas, with a cartilage bar completing the foramen cranially. Between 6 and 16 weeks the bar forming the cranial bony border of the LVF ossified in its preexisting cartilage anlage. In mature dogs, the LVF was present in the craniolateral aspect of the arch of the atlas and was recognized on lateral radiographs. The vertebral artery and vein, and first cervical nerve passed through the LVF and the atlantooccipital joint capsule and dorsal membrane attached to the cranial border of the LVF. In one dog the cranial border of the LVF of the atlas was incompletely ossified bilaterally. This developmental variant was compared with variations in man and other mammals, and with proatlas neural arch derivatives.

Postnatal ossification centers of the atlas and axis in miniature schnauzers.

Postnatal ossification of the atlas and axis was studied in Miniature Schnauzers by examining alizarin-stained bone clearings, cleaned dry bones, radiographs, histologic sections, and arterially perfused bone clearings. Sixty-two pups (1 day to 16 weeks old) and 4 adults were examined. In 1-day-old pups, the atlas consisted of 3 separate ossification centers: a left and right neural arch center and midventrally, the intercentrum 1, which formed the body of the atlas. The axis contained 4 separate ossification centers: a left and right neural arch center; centrum 2 in the main part of the axis body; and centrum 1, which formed the caudal part of the dens and the cranial part of the axis body. By 6 weeks of age, the epiphysis on the caudal end of the axis body had begun to ossify. At this time, the intercentrum 2, which developed as a cuboidal ossification center intercalated between centrum 1 and centrum 2 in the middle of the cranial half of the axis body, also began to ossify. The centrum of the proatlas, which formed the apex of the dens, was first seen ossified in a 9-week-old pup. These 10 ossification centers were seen as constant and separate elements. In all dogs, the dens developed from 2 separate ossification centers: the centrum of the proatlas formed the cranial one-quarter, and centrum 1 formed the caudal three-quarters. Dens dysplasia is unlikely to be a result of failure of development of one of the ossification centers for the dens.(ABSTRACT TRUNCATED AT 250 WORDS)

Atlantoaxial subluxation and absence of transverse ligament of the atlas in a dog.

Absence of the transverse ligament of the atlas was diagnosed at necropsy in an 8-month-old Shih Tzu with radiographic signs of atlantoaxial subluxation. Symmetric ataxia, tetraparesis, and signs of pain in the vertebral canal suggested a lesion in the cervical portion of the spinal cord. Necropsy revealed absence of the transverse ligament of the atlas and malformation of dens and atlas. In addition, the alar ligaments were distinct and thick, and the atlanto-occipital and atlantoaxial joint capsules were markedly thicker than normal. Histologic examination revealed focal compressive myelopathy of the spinal cord at the level of the atlantoaxial joint.

Morphology and embryological interpretation of a congenital occipito-atlanto-axial malformation in a dog.

A clinical, radiological, and morphological study of a congenital occipito-atlanto-axial malformation in a 13-week-old male Saint Bernard dog that became suddenly tetraplegic at 8 weeks is described. The dog was recumbent, had generalized muscle atrophy, but was alert and responsive. Pain was elicited when the head-neck junction and the cervical vertebrae were palpated, and a bony abnormality was palpated at the occiput and atlas. Clinical signs of upper motor neuron and general proprioceptive deficits in all four limbs were compatible with a focal lesion in the cervical spinal cord. Plain radiographs of the head and neck revealed malformation of the occipital bones, atlas, and axis, unilateral atlanto-occipital fusion, and atlanto-axial subluxation. At necropsy the right half of the atlantal neural arch was fused to the right exoccipital bone. On the axis, the dens was small, malformed, and deviated to the left; the transverse processes were enlarged; and the spinous process was small with a cleft caudally. The spinal cord was severely compressed at the level of the atlanto-axial articulation, and histological examination revealed extensive loss of neuronal cell bodies, axons, myelin, and the central canal. Reactive astrogliosis was also extensive. After a discussion of normal and abnormal development of the vertebral column and its joints, it was concluded that a failure of normal joint development at about 30 days of gestation in the dog could lead to congenital occipito-atlanto-axial malformation.

Adenocarcinoma of the lacrimal gland with metastasis to the preauricular lymph nodes and parotid gland.

We describe a 68-year-old man with adenocarcinoma of the lacrimal gland with metastatic spread to the ipsilateral preauricular lymph nodes and parotid gland. The patient died of metastatic lung involvement. Metastasis to the preauricular nodes and parotid gland by malignant lacrimal gland tumours is rare.

Prenatal development of the composite occipito-atlanto-axial synovial joint cavity in the dog.

In the dog, the synovial cavities of the atlanto-occipital and atlanto-axial joints communicated to form a single large composite joint cavity. The prenatal development of this composite occipito-atlanto-axial joint cavity was studied by examining 26 serially sectioned dog embryos and fetuses that ranged in size from 19 to 68 mm crown-rump length, and were between 30 and 42 days of gestational age. In the composite occipito-atlanto-axial joint, trilaminar interzones developed at 19-22 mm (30-31 days), joint cavities opened at 27-32 mm (33-34 days), and the atlanto-occipital and atlanto-axial cavities first communicated at 48 mm (37 days).

Familial congenital occipitoatlantoaxial malformation (OAAM) in the Arabian horse.

Familial occipitalization of the atlas with atlantalization of the axis was defined as a single congenital disease in Arabian horses following a clinical, radiologic, and morphologic study of 16 horses with congenital malformations of the occiput, atlas, and axis, and from a study of three reported cases. The constant morphologic features were interpreted as congenital atlantooccipital fusion, hypoplasia of the atlas and dens, malformation of the axis, and modification of the atlantoaxial joint. Atlantoaxial subluxation was also a frequent finding. The clinical syndromes shown by these horses were variable but were broadly classified into four groups. Neurologic signs varied from symmetric ataxia, with hypometria and tetraparesis to tetraplegia. These often progressive clinical signs were due to a progressive and focal compressive myelopathy of the proximal cervical spinal cord. Pedigree analysis demonstrated the familial nature of this occipitoatlantoaxial malformation seen in horses of only the Arabian breed.

Congenital malformations of the flipper in three West Indian manatees, Trichechus manatus, and a proposed mechanism for development of ectrodactyly and cleft hand in mammals.

Three cases of congenital ectrodactyly of the flipper in the manatee are described, including one case of bilaterally-symmetrical cleft hand. A hypothesis assumes that a defect in the apical ectodermal ridge (AER) in the developing hand plate of the early embryo is the initiating factor in the development of ectrodactylous and cleft hand malformations in man and other mammals. Variations in the site, extent, and time of the AER defect will account for many of the morphologic variations observed in these congenital malformations.

Occipito-atlanto-axial malformation with atlanto-axial subluxation in an ataxic calf.

Occipito-atlanto-axial malformation with atlanto-axial subluxation was diagnosed radiographically in a 4-day-old Holstein calf with a short neck, symmetric ataxia, and tetraparesis, indicative of a cervical spinal cord lesion. Necropsy confirmed the clinical diagnosis and revealed ribs on C-7, with partial fusion of C-7 and T-1. Histologic examination revealed focal degeneration of the spinal cord in the second cervical segment at the level of the atlanto-axial joint and extensive secondary neuronal fiber degeneration possibly caused by spinal cord trauma that occurred in utero.

Intracranial plasmacytoma associated with multiple myeloma.

A 58-year-old man with multiple myeloma presented with a 3-month history of a sensation of occipital pressure, transient blurring of vision and increased bone pain. Funduscopic examination revealed disc swelling, tortuous veins and superficial retinal hemorrhages simulating early hyperviscosity syndrome. Clinical investigation and computerized tomography, however, indicated that an intracranial plasmacytoma was the cause of his papilledema. Cobalt 60 beam therapy and vincristine were added to his treatment regimen. Seven weeks later the intracranial tumour had almost totally disappeared. Symptomatic cerebral compression from an intracranial plasmacytoma associated with systemic disease is uncommon. The diagnosis and management are reviewed.

The effect of metocurine and metocurine-pancuronium combination on intraocular pressure.

Maintenance of a normal to low intraocular pressure during ocular surgery is of critical importance. The prime considerations for anaesthetic management include adequate depth of anaesthesia, normal carbon dioxide and arterial oxygen tensions, stable cardiovascular status and avoidance of stimuli likely to raise central venous pressure. Non-depolarizing muscle relaxants are associated with a reduction in intraocular pressure. Metocurine, a non-depolarizing relaxant, formerly known as dimethyltubocurarine, has been recently reintroduced into clinical practice. Metocurine has been reported to be 1.8 times more potent than d-tubocurarine and has the clinically advantageous cardiovascular effects of stable heart rate and mean blood pressure with minimal associated histamine release. When combined with pancuronium, metocurine potentiates the neuromuscular blocking properties, so that small doses of both drugs in combination produce effective neuromuscular block. This study was designed to assess the suitability of metocurine 0.3 mg.kg-1 and metocurine 0.08 mg.kg-1 plus pancuronium 0.02 mg.kg-1 as muscle relaxants for ocular surgery. The results demonstrated that metocurine and metocurine-pancuronium combination in the above doses combined with sodium thiopentone 5 mg.kg-1 produced ideal conditions for intubation of the trachea in 4.45 (+/- 0.19 SE) minutes and 4.35 (+/- 0.16 SE) minutes respectively. In both treatment groups intraocular pressure was reduced below control values and a pattern of intraocular pressure stability ideal for ocular surgery was obtained during the 10 minutes observation period. The delayed onset of sufficient paralysis for tracheal intubation - 4.45 (+/- 0.19 SE) minutes for metocurine and 4.35 (+/- 0.16 SE) minutes for the combination - makes these techniques unsuitable for emergency ocular surgery because of the long interval when the airway is unprotected.

The effect of intravenous diazepam on rise of intraocular pressure following succinylcholine.

Because succinylcholine raised intraocular pressure, its use to facilitate tracheal intubation for ocular surgery, especially in emergency open-eye cases, has been a controversial topic among anaesthetists for more than two decades. In recent years, intravenous diazepam pretreatment before succinylcholine has been reported to reduce the untoward side effects of myalgia, and elevation of serum potassium and creatine phosphokinase. This study was designed to assess the effect of pretreatment with intravenous diazepam 0.1 mg kg-1 on control (base-line) intraocular pressure and to determine if such pretreatment diminished the rise in intraocular pressure following the standard anaesthesia induction sequence of thiopentone 3 - 5 mg kg-1., followed by tracheal intubation. Such diazepam pretreatment was shown to reduce the intraocular pressure from control levels and to diminish the rise of intraocular pressure following succinylcholine and tracheal intubation. Because succinylcholine produces rapid onset of neuromuscular block for tracheal intubation and since only minor intraocular pressure elevation occurs following thiopentone and succinylcholine in patients pretreated with diazepam, its use in ocular surgery, including emergency open-eye cases, can be rationally advocated. The addition of 0.6 mg kg-1 d-tubocurarine to the diazepam pretreatment did not produce a further reduction of the increase of intraocular pressure following succinylcholine.

Congenital occipitoatlantoaxial malformations in the horse.

From a clinical, radiological and morphological study of 9 horses with congenital malformations of the occiput, atlas and axis, and from a study of 2 reported cases, 3 diseases were defined: A. Familial occipitalisation of the atlas with atlantalisation of the axis in Arabian horses (7 cases in this report and the case reported by Leipold, et al., 1974). These horses had congenital atlantooccipital fusion, hypoplasia of the atlas and dens, malformation of the axis and modification of the atlantoaxial joint. B. Congenital asymmetrical occipitoatlantoaxial malformation (2 cases in this report). A Standardbred and a Morgan horse had atlantooccipital fusion, a wedge shaped vertebral piece attached to the caudal end of the axis and sigmoid scoliosis of the cervical vertebrae. C. Asymmetrical atlantooccipital fusion (the case reported by Schmaltz, 1915). This horse of an unknown breed had asymmetrical fusion between the atlas and occiput and cervical scoliosis. The clinical syndromes shown by horses with these malformations were variable but were broadly classified as: 1. Foal dead at birth, seen in one foal with A. 2. Tetraparesis at birth, seen in 5 foals with A. These foals were born with signs varying from tetraparesis to tetraplegia. 3. Progressive ataxia, seen in 2 foals with A. Clinical signs were due to a progressive focal cervical compressive myelopathy. 4. Congenital cervical scoliosis/deviated head, seen in the 2 horses with B and the horse with C. These horses had no signs of spinal cord or brain disease. The diagnoses were made clinically by palpation of the occipitoatlantoaxial region and were confirmed radiographically and/or by post mortem examination in all except one case. Pedigree analysis showed the familial nature of the particular occipitoatlantoaxial malformation seen in horses of only the Arabian breed.

The value of pancuronium in prolonged intraocular operations.

We wished to determine the effectiveness of Pancuronium, a non-depolarizing muscle relaxant, in prolonged intraocular operations. We compared the variations in intraocular pressure when using four different methods of induction of general anesthesia. With Pancuronium the intraocular pressure fell initially and then rose to just below pre-induction levels and remained there. Our study suggests that pancuronium stabilizes intraocular pressure at a level which is highly desirable for intraocular surgery.

Ophthalmic manifestations of multiple endocrine neoplasia, type three.

We report the case of a patient with multiple endocrine neoplasia type three, which was first diagnosed by members of the department of Ophthalmology. He was found to have multiple mucosal neuromata and medullary thyroid carcinoma. The ocular components of this syndrome include visible corneal nerves, conjunctival neuromas, thickened lids, anterior displacement of the cilia and a "dry eye" syndrome. The major systemic components are medullary thyroid carcinoma and pheochromocytoma. It is important that the Ophthalmologist recognize the ophthalmic manifestations of this syndrome so that early diagnosis and treatment may be possible.

Internal ophthalmoplegia following chickenpox.

A six year old girl with a six day history of varicella presented with a fixed dilated pupil, paralysis of accomodation and an anterior uveitis in the left eye. The anterior uveitis rapidly resolved but the internal ophthalmoplegia has persisted for fifteen months. Four similar cases are reviewed.